diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ebd026658ff95..a717a5efcaba7 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -347,7 +347,6 @@ import {
     getNamespaceDeclarationNode,
     getNewTargetContainer,
     getNonAugmentationDeclaration,
-    getNonModifierTokenPosOfNode,
     getNormalizedAbsolutePath,
     getObjectFlags,
     getOriginalNode,
@@ -48104,12 +48103,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (isIdentifier(node.name)) {
                 checkCollisionsForDeclarationName(node, node.name);
                 if (!(node.flags & (NodeFlags.Namespace | NodeFlags.GlobalAugmentation))) {
-                    const sourceFile = getSourceFileOfNode(node);
-                    const pos = getNonModifierTokenPosOfNode(node);
-                    const span = getSpanOfTokenAtPosition(sourceFile, pos);
-                    suggestionDiagnostics.add(
-                        createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.A_namespace_declaration_should_not_be_declared_using_the_module_keyword_Please_use_the_namespace_keyword_instead),
-                    );
+                    error(node.name, Diagnostics.A_namespace_declaration_should_not_be_declared_using_the_module_keyword_Please_use_the_namespace_keyword_instead);
                 }
             }
 
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index c21fd11e5c7bf..03f5f19a69877 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1821,9 +1821,8 @@
         "code": 1539
     },
     "A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.": {
-        "category": "Suggestion",
-        "code": 1540,
-        "reportsDeprecated": true
+        "category": "Error",
+        "code": 1540
     },
     "Type-only import of an ECMAScript module from a CommonJS module must have a 'resolution-mode' attribute.": {
         "category": "Error",
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 4939145c433c7..d346f22cad467 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -1282,16 +1282,6 @@ export function getNonDecoratorTokenPosOfNode(node: Node, sourceFile?: SourceFil
     return skipTrivia((sourceFile || getSourceFileOfNode(node)).text, lastDecorator.end);
 }
 
-/** @internal */
-export function getNonModifierTokenPosOfNode(node: Node, sourceFile?: SourceFileLike): number {
-    const lastModifier = !nodeIsMissing(node) && canHaveModifiers(node) && node.modifiers ? last(node.modifiers) : undefined;
-    if (!lastModifier) {
-        return getTokenPosOfNode(node, sourceFile);
-    }
-
-    return skipTrivia((sourceFile || getSourceFileOfNode(node)).text, lastModifier.end);
-}
-
 /** @internal */
 export function getSourceTextOfNodeFromSourceFile(sourceFile: SourceFile, node: Node, includeTrivia = false): string {
     return getTextOfNodeFromSourceText(sourceFile.text, node, includeTrivia);
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.errors.txt b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.errors.txt
index 715c39f146bb3..c62c22a8b8117 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.errors.txt
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.errors.txt
@@ -14,7 +14,7 @@ TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts(26,26): error
         }
     }
     
-    module A{
+    namespace A{
         // expected error
         export class Point {
                      ~~~~~
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.js b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.js
index 47a5b2126df58..f5285b0f7de52 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.js
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.js
@@ -8,7 +8,7 @@ namespace A {
     }
 }
 
-module A{
+namespace A{
     // expected error
     export class Point {
         origin: number;
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.symbols b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.symbols
index 0a717333d4528..bbf68ed6428a2 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.symbols
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.symbols
@@ -15,12 +15,12 @@ namespace A {
     }
 }
 
-module A{
+namespace A{
 >A : Symbol(A, Decl(TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts, 0, 0), Decl(TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts, 5, 1))
 
     // expected error
     export class Point {
->Point : Symbol(Point, Decl(TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts, 7, 9))
+>Point : Symbol(Point, Decl(TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts, 7, 12))
 
         origin: number;
 >origin : Symbol(Point.origin, Decl(TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts, 9, 24))
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.types b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.types
index bf99414a04bc1..e0f784f6aa484 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.types
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.types
@@ -19,7 +19,7 @@ namespace A {
     }
 }
 
-module A{
+namespace A{
 >A : typeof A
 >  : ^^^^^^^^
 
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.js b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.js
index be607bb5c0a85..e7ee79902558f 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.js
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.js
@@ -5,7 +5,7 @@ namespace A.B {
     export var x: number;
 }
 
-module A{ 
+namespace A{ 
     namespace B {
         export var x: string;
     }
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.symbols b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.symbols
index 7c78b6d104bbb..9fadf3a04f230 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.symbols
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.symbols
@@ -9,11 +9,11 @@ namespace A.B {
 >x : Symbol(x, Decl(TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts, 1, 14))
 }
 
-module A{ 
+namespace A{ 
 >A : Symbol(A, Decl(TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts, 0, 0), Decl(TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts, 2, 1))
 
     namespace B {
->B : Symbol(B, Decl(TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts, 4, 9))
+>B : Symbol(B, Decl(TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts, 4, 12))
 
         export var x: string;
 >x : Symbol(x, Decl(TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts, 6, 18))
diff --git a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.types b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.types
index c32af0d51d3a7..0464cd9ad5fea 100644
--- a/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.types
+++ b/tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.types
@@ -12,7 +12,7 @@ namespace A.B {
 >  : ^^^^^^
 }
 
-module A{ 
+namespace A{ 
 >A : typeof A
 >  : ^^^^^^^^
 
diff --git a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.errors.txt b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.errors.txt
index 11b3093de6a53..c31195f2ad4d1 100644
--- a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.errors.txt
+++ b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.errors.txt
@@ -3,7 +3,7 @@ cannotInvokeNewOnErrorExpression.ts(5,22): error TS1011: An element access expre
 
 
 ==== cannotInvokeNewOnErrorExpression.ts (2 errors) ====
-    module M
+    namespace M
     {
         class ClassA {}
     }
diff --git a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.js b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.js
index 548c413fa674c..4b5346fbfad02 100644
--- a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.js
+++ b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts] ////
 
 //// [cannotInvokeNewOnErrorExpression.ts]
-module M
+namespace M
 {
     class ClassA {}
 }
diff --git a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.symbols b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.symbols
index 995b68c4cda61..ece816d502e3f 100644
--- a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.symbols
+++ b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts] ////
 
 === cannotInvokeNewOnErrorExpression.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(cannotInvokeNewOnErrorExpression.ts, 0, 0))
 {
     class ClassA {}
diff --git a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.types b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.types
index 1cfc2883866f0..3609269d95ff6 100644
--- a/tests/baselines/reference/cannotInvokeNewOnErrorExpression.types
+++ b/tests/baselines/reference/cannotInvokeNewOnErrorExpression.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts] ////
 
 === cannotInvokeNewOnErrorExpression.ts ===
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/circularModuleImports.errors.txt b/tests/baselines/reference/circularModuleImports.errors.txt
index d7fdcefcfdf47..55124d0dccf26 100644
--- a/tests/baselines/reference/circularModuleImports.errors.txt
+++ b/tests/baselines/reference/circularModuleImports.errors.txt
@@ -2,7 +2,7 @@ circularModuleImports.ts(5,5): error TS2303: Circular definition of import alias
 
 
 ==== circularModuleImports.ts (1 errors) ====
-    module M
+    namespace M
      
     {
      
diff --git a/tests/baselines/reference/circularModuleImports.js b/tests/baselines/reference/circularModuleImports.js
index 7457998dafa96..129feb9cbd247 100644
--- a/tests/baselines/reference/circularModuleImports.js
+++ b/tests/baselines/reference/circularModuleImports.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/circularModuleImports.ts] ////
 
 //// [circularModuleImports.ts]
-module M
+namespace M
  
 {
  
diff --git a/tests/baselines/reference/circularModuleImports.symbols b/tests/baselines/reference/circularModuleImports.symbols
index c731f998229a4..7eb4444d06caf 100644
--- a/tests/baselines/reference/circularModuleImports.symbols
+++ b/tests/baselines/reference/circularModuleImports.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/circularModuleImports.ts] ////
 
 === circularModuleImports.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(circularModuleImports.ts, 0, 0))
  
 {
diff --git a/tests/baselines/reference/circularModuleImports.types b/tests/baselines/reference/circularModuleImports.types
index a304a9e6d77fa..f50795d85d625 100644
--- a/tests/baselines/reference/circularModuleImports.types
+++ b/tests/baselines/reference/circularModuleImports.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/circularModuleImports.ts] ////
 
 === circularModuleImports.ts ===
-module M
+namespace M
  
 {
  
diff --git a/tests/baselines/reference/cloduleTest1.js b/tests/baselines/reference/cloduleTest1.js
index a368d0f8b8ba4..5871181863b9a 100644
--- a/tests/baselines/reference/cloduleTest1.js
+++ b/tests/baselines/reference/cloduleTest1.js
@@ -5,7 +5,7 @@
   interface $ {
       addClass(className: string): $;
   }
-  module $ {
+  namespace $ {
     export interface AjaxSettings {
     }
     export function ajax(options: AjaxSettings) { }
diff --git a/tests/baselines/reference/cloduleTest1.symbols b/tests/baselines/reference/cloduleTest1.symbols
index 10744b33a50b7..0ada382a6a5c4 100644
--- a/tests/baselines/reference/cloduleTest1.symbols
+++ b/tests/baselines/reference/cloduleTest1.symbols
@@ -14,16 +14,16 @@
 >className : Symbol(className, Decl(cloduleTest1.ts, 2, 15))
 >$ : Symbol($, Decl(cloduleTest1.ts, 0, 0), Decl(cloduleTest1.ts, 0, 42), Decl(cloduleTest1.ts, 3, 3))
   }
-  module $ {
+  namespace $ {
 >$ : Symbol($, Decl(cloduleTest1.ts, 0, 0), Decl(cloduleTest1.ts, 0, 42), Decl(cloduleTest1.ts, 3, 3))
 
     export interface AjaxSettings {
->AjaxSettings : Symbol(AjaxSettings, Decl(cloduleTest1.ts, 4, 12))
+>AjaxSettings : Symbol(AjaxSettings, Decl(cloduleTest1.ts, 4, 15))
     }
     export function ajax(options: AjaxSettings) { }
 >ajax : Symbol(ajax, Decl(cloduleTest1.ts, 6, 5))
 >options : Symbol(options, Decl(cloduleTest1.ts, 7, 25))
->AjaxSettings : Symbol(AjaxSettings, Decl(cloduleTest1.ts, 4, 12))
+>AjaxSettings : Symbol(AjaxSettings, Decl(cloduleTest1.ts, 4, 15))
   }
   var it: $ = $('.foo').addClass('bar');
 >it : Symbol(it, Decl(cloduleTest1.ts, 9, 5))
diff --git a/tests/baselines/reference/cloduleTest1.types b/tests/baselines/reference/cloduleTest1.types
index 30d56ceaeb475..c9976b2dfac3f 100644
--- a/tests/baselines/reference/cloduleTest1.types
+++ b/tests/baselines/reference/cloduleTest1.types
@@ -14,7 +14,7 @@
 >className : string
 >          : ^^^^^^
   }
-  module $ {
+  namespace $ {
 >$ : typeof $
 >  : ^^^^^^^^
 
diff --git a/tests/baselines/reference/cloduleWithRecursiveReference.js b/tests/baselines/reference/cloduleWithRecursiveReference.js
index 06400b2629a9d..6a5e57b64b76f 100644
--- a/tests/baselines/reference/cloduleWithRecursiveReference.js
+++ b/tests/baselines/reference/cloduleWithRecursiveReference.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/cloduleWithRecursiveReference.ts] ////
 
 //// [cloduleWithRecursiveReference.ts]
-module M
+namespace M
 {
   export class C {  }
   export namespace C {
diff --git a/tests/baselines/reference/cloduleWithRecursiveReference.symbols b/tests/baselines/reference/cloduleWithRecursiveReference.symbols
index ff0aae85cdbd1..08d99dc3d7224 100644
--- a/tests/baselines/reference/cloduleWithRecursiveReference.symbols
+++ b/tests/baselines/reference/cloduleWithRecursiveReference.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/cloduleWithRecursiveReference.ts] ////
 
 === cloduleWithRecursiveReference.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(cloduleWithRecursiveReference.ts, 0, 0))
 {
   export class C {  }
diff --git a/tests/baselines/reference/cloduleWithRecursiveReference.types b/tests/baselines/reference/cloduleWithRecursiveReference.types
index 43ffa814195df..0f1a6b0b2343e 100644
--- a/tests/baselines/reference/cloduleWithRecursiveReference.types
+++ b/tests/baselines/reference/cloduleWithRecursiveReference.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/cloduleWithRecursiveReference.ts] ////
 
 === cloduleWithRecursiveReference.ts ===
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/declareDottedExtend.js b/tests/baselines/reference/declareDottedExtend.js
index d0e1ec59137fc..81ddd799f0b1e 100644
--- a/tests/baselines/reference/declareDottedExtend.js
+++ b/tests/baselines/reference/declareDottedExtend.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/declareDottedExtend.ts] ////
 
 //// [declareDottedExtend.ts]
-declare module A.B
+declare namespace A.B
 {
     export class C{ }
 }
diff --git a/tests/baselines/reference/declareDottedExtend.symbols b/tests/baselines/reference/declareDottedExtend.symbols
index 48cb9e6a3db1d..01c8539a08d93 100644
--- a/tests/baselines/reference/declareDottedExtend.symbols
+++ b/tests/baselines/reference/declareDottedExtend.symbols
@@ -1,9 +1,9 @@
 //// [tests/cases/compiler/declareDottedExtend.ts] ////
 
 === declareDottedExtend.ts ===
-declare module A.B
+declare namespace A.B
 >A : Symbol(A, Decl(declareDottedExtend.ts, 0, 0))
->B : Symbol(B, Decl(declareDottedExtend.ts, 0, 17))
+>B : Symbol(B, Decl(declareDottedExtend.ts, 0, 20))
 {
     export class C{ }
 >C : Symbol(C, Decl(declareDottedExtend.ts, 1, 1))
@@ -12,7 +12,7 @@ declare module A.B
 import ab = A.B;
 >ab : Symbol(ab, Decl(declareDottedExtend.ts, 3, 1))
 >A : Symbol(A, Decl(declareDottedExtend.ts, 0, 0))
->B : Symbol(ab, Decl(declareDottedExtend.ts, 0, 17))
+>B : Symbol(ab, Decl(declareDottedExtend.ts, 0, 20))
 
 class D extends ab.C{ }
 >D : Symbol(D, Decl(declareDottedExtend.ts, 5, 16))
@@ -23,8 +23,8 @@ class D extends ab.C{ }
 class E extends A.B.C{ }
 >E : Symbol(E, Decl(declareDottedExtend.ts, 7, 23))
 >A.B.C : Symbol(ab.C, Decl(declareDottedExtend.ts, 1, 1))
->A.B : Symbol(ab, Decl(declareDottedExtend.ts, 0, 17))
+>A.B : Symbol(ab, Decl(declareDottedExtend.ts, 0, 20))
 >A : Symbol(A, Decl(declareDottedExtend.ts, 0, 0))
->B : Symbol(ab, Decl(declareDottedExtend.ts, 0, 17))
+>B : Symbol(ab, Decl(declareDottedExtend.ts, 0, 20))
 >C : Symbol(ab.C, Decl(declareDottedExtend.ts, 1, 1))
 
diff --git a/tests/baselines/reference/declareDottedExtend.types b/tests/baselines/reference/declareDottedExtend.types
index ffd3fc1c33a93..c057d1664edf8 100644
--- a/tests/baselines/reference/declareDottedExtend.types
+++ b/tests/baselines/reference/declareDottedExtend.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/declareDottedExtend.ts] ////
 
 === declareDottedExtend.ts ===
-declare module A.B
+declare namespace A.B
 >A : typeof A
 >  : ^^^^^^^^
 >B : typeof B
diff --git a/tests/baselines/reference/dottedModuleName2.js b/tests/baselines/reference/dottedModuleName2.js
index 4586e6a17c54a..65c4e4cccf4c5 100644
--- a/tests/baselines/reference/dottedModuleName2.js
+++ b/tests/baselines/reference/dottedModuleName2.js
@@ -22,7 +22,7 @@ var tmpOK = AA.B.x;
 var tmpError = A.B.x;
 
 
-module A.B.C
+namespace A.B.C
  
 {
  
@@ -32,7 +32,7 @@ module A.B.C
  
  
  
-module M
+namespace M
  
 {
  
diff --git a/tests/baselines/reference/dottedModuleName2.symbols b/tests/baselines/reference/dottedModuleName2.symbols
index 3f176241d0f60..2512b81402601 100644
--- a/tests/baselines/reference/dottedModuleName2.symbols
+++ b/tests/baselines/reference/dottedModuleName2.symbols
@@ -3,7 +3,7 @@
 === dottedModuleName2.ts ===
 namespace A.B {
 >A : Symbol(A, Decl(dottedModuleName2.ts, 0, 0), Decl(dottedModuleName2.ts, 18, 21))
->B : Symbol(B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 9))
+>B : Symbol(B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 12))
  
   export var x = 1;
 >x : Symbol(x, Decl(dottedModuleName2.ts, 2, 12))
@@ -34,16 +34,16 @@ var tmpOK = AA.B.x;
 var tmpError = A.B.x;
 >tmpError : Symbol(tmpError, Decl(dottedModuleName2.ts, 18, 3))
 >A.B.x : Symbol(A.B.x, Decl(dottedModuleName2.ts, 2, 12))
->A.B : Symbol(A.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 9))
+>A.B : Symbol(A.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 12))
 >A : Symbol(A, Decl(dottedModuleName2.ts, 0, 0), Decl(dottedModuleName2.ts, 18, 21))
->B : Symbol(A.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 9))
+>B : Symbol(A.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 12))
 >x : Symbol(A.B.x, Decl(dottedModuleName2.ts, 2, 12))
 
 
-module A.B.C
+namespace A.B.C
 >A : Symbol(A, Decl(dottedModuleName2.ts, 0, 0), Decl(dottedModuleName2.ts, 18, 21))
->B : Symbol(B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 9))
->C : Symbol(C, Decl(dottedModuleName2.ts, 21, 11))
+>B : Symbol(B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 12))
+>C : Symbol(C, Decl(dottedModuleName2.ts, 21, 14))
  
 {
  
@@ -54,7 +54,7 @@ module A.B.C
  
  
  
-module M
+namespace M
 >M : Symbol(M, Decl(dottedModuleName2.ts, 27, 1))
  
 {
@@ -66,13 +66,13 @@ module M
     import X2 = A.B;
 >X2 : Symbol(X2, Decl(dottedModuleName2.ts, 35, 18))
 >A : Symbol(X1, Decl(dottedModuleName2.ts, 0, 0), Decl(dottedModuleName2.ts, 18, 21))
->B : Symbol(X1.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 9))
+>B : Symbol(X1.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 12))
  
     import X3 = A.B.C;
 >X3 : Symbol(X3, Decl(dottedModuleName2.ts, 37, 20))
 >A : Symbol(X1, Decl(dottedModuleName2.ts, 0, 0), Decl(dottedModuleName2.ts, 18, 21))
->B : Symbol(X1.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 9))
->C : Symbol(X2.C, Decl(dottedModuleName2.ts, 21, 11))
+>B : Symbol(X1.B, Decl(dottedModuleName2.ts, 0, 12), Decl(dottedModuleName2.ts, 21, 12))
+>C : Symbol(X2.C, Decl(dottedModuleName2.ts, 21, 14))
  
 }
 
diff --git a/tests/baselines/reference/dottedModuleName2.types b/tests/baselines/reference/dottedModuleName2.types
index cd7ec8d5de88f..13430275a7181 100644
--- a/tests/baselines/reference/dottedModuleName2.types
+++ b/tests/baselines/reference/dottedModuleName2.types
@@ -62,7 +62,7 @@ var tmpError = A.B.x;
 >  : ^^^^^^
 
 
-module A.B.C
+namespace A.B.C
 >A : typeof A
 >  : ^^^^^^^^
 >B : typeof B
@@ -82,7 +82,7 @@ module A.B.C
  
  
  
-module M
+namespace M
  
 {
  
diff --git a/tests/baselines/reference/escapedIdentifiers.errors.txt b/tests/baselines/reference/escapedIdentifiers.errors.txt
new file mode 100644
index 0000000000000..c1c08718cd21f
--- /dev/null
+++ b/tests/baselines/reference/escapedIdentifiers.errors.txt
@@ -0,0 +1,125 @@
+escapedIdentifiers.ts(25,16): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+
+
+==== escapedIdentifiers.ts (1 errors) ====
+    /*
+        0 .. \u0030
+        9 .. \u0039
+    
+        A .. \u0041
+        Z .. \u005a
+    
+        a .. \u0061
+        z .. \u00za
+    */
+    
+    // var decl
+    var \u0061 = 1;
+    a ++;
+    \u0061 ++;
+    
+    var b = 1;
+    b ++;
+    \u0062 ++;
+    
+    // modules
+    namespace moduleType1 { 
+        export var baz1: number;
+    }
+    declare module moduleType\u0032 { 
+                   ~~~~~~~~~~~~~~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+        export var baz2: number;
+    }
+    
+    moduleType1.baz1 = 3;
+    moduleType\u0031.baz1 = 3;
+    moduleType2.baz2 = 3;
+    moduleType\u0032.baz2 = 3;
+    
+    // classes
+    
+    class classType1 { 
+        public foo1: number;
+    }
+    class classType\u0032 { 
+        public foo2: number;
+    }
+    
+    var classType1Object1 = new classType1();
+    classType1Object1.foo1 = 2;
+    var classType1Object2 = new classType\u0031();
+    classType1Object2.foo1 = 2;
+    var classType2Object1 = new classType2();
+    classType2Object1.foo2 = 2;
+    var classType2Object2 = new classType\u0032();
+    classType2Object2.foo2 = 2;
+    
+    // interfaces
+    interface interfaceType1 { 
+        bar1: number;
+    }
+    interface interfaceType\u0032 { 
+        bar2: number;
+    }
+    
+    var interfaceType1Object1 = <interfaceType1>{ bar1: 0 };
+    interfaceType1Object1.bar1 = 2;
+    var interfaceType1Object2 = <interfaceType\u0031>{ bar1: 0 };
+    interfaceType1Object2.bar1 = 2;
+    var interfaceType2Object1 = <interfaceType2>{ bar2: 0 };
+    interfaceType2Object1.bar2 = 2;
+    var interfaceType2Object2 = <interfaceType\u0032>{ bar2: 0 };
+    interfaceType2Object2.bar2 = 2;
+    
+    
+    // arguments
+    class testClass { 
+        public func(arg1: number, arg\u0032: string, arg\u0033: boolean, arg4: number) { 
+            arg\u0031 = 1;
+            arg2 = 'string';
+            arg\u0033 = true;
+            arg4 = 2;
+        }
+    }
+    
+    // constructors
+    class constructorTestClass { 
+        constructor (public arg1: number,public arg\u0032: string,public arg\u0033: boolean,public arg4: number) { 
+        }
+    }
+    var constructorTestObject = new constructorTestClass(1, 'string', true, 2);
+    constructorTestObject.arg\u0031 = 1;
+    constructorTestObject.arg2 = 'string';
+    constructorTestObject.arg\u0033 = true;
+    constructorTestObject.arg4 = 2;
+    
+    // Lables
+    
+    l\u0061bel1: 
+        while (false)
+        {  
+           while(false)
+               continue label1;  // it will go to next iteration of outer loop 
+        } 
+    
+    label2: 
+        while (false)
+        {  
+           while(false)
+               continue l\u0061bel2;  // it will go to next iteration of outer loop 
+        } 
+    
+    label3: 
+        while (false)
+        {  
+           while(false)
+               continue label3;  // it will go to next iteration of outer loop 
+        } 
+    
+    l\u0061bel4: 
+        while (false)
+        {  
+           while(false)
+               continue l\u0061bel4;  // it will go to next iteration of outer loop 
+        } 
\ No newline at end of file
diff --git a/tests/baselines/reference/escapedIdentifiers.js b/tests/baselines/reference/escapedIdentifiers.js
index f6d19e5ede628..308e0b40db6af 100644
--- a/tests/baselines/reference/escapedIdentifiers.js
+++ b/tests/baselines/reference/escapedIdentifiers.js
@@ -25,7 +25,7 @@ b ++;
 namespace moduleType1 { 
     export var baz1: number;
 }
-module moduleType\u0032 { 
+declare module moduleType\u0032 { 
     export var baz2: number;
 }
 
@@ -143,9 +143,6 @@ b++;
 var moduleType1;
 (function (moduleType1) {
 })(moduleType1 || (moduleType1 = {}));
-var moduleType\u0032;
-(function (moduleType\u0032) {
-})(moduleType\u0032 || (moduleType\u0032 = {}));
 moduleType1.baz1 = 3;
 moduleType\u0031.baz1 = 3;
 moduleType2.baz2 = 3;
diff --git a/tests/baselines/reference/escapedIdentifiers.symbols b/tests/baselines/reference/escapedIdentifiers.symbols
index 762f7898cfd30..acefacf43c13e 100644
--- a/tests/baselines/reference/escapedIdentifiers.symbols
+++ b/tests/baselines/reference/escapedIdentifiers.symbols
@@ -38,7 +38,7 @@ namespace moduleType1 {
     export var baz1: number;
 >baz1 : Symbol(baz1, Decl(escapedIdentifiers.ts, 22, 14))
 }
-module moduleType\u0032 { 
+declare module moduleType\u0032 { 
 >moduleType\u0032 : Symbol(moduleType\u0032, Decl(escapedIdentifiers.ts, 23, 1))
 
     export var baz2: number;
diff --git a/tests/baselines/reference/escapedIdentifiers.types b/tests/baselines/reference/escapedIdentifiers.types
index 9cd78aad95682..1dc9de2b70a31 100644
--- a/tests/baselines/reference/escapedIdentifiers.types
+++ b/tests/baselines/reference/escapedIdentifiers.types
@@ -58,7 +58,7 @@ namespace moduleType1 {
 >baz1 : number
 >     : ^^^^^^
 }
-module moduleType\u0032 { 
+declare module moduleType\u0032 { 
 >moduleType\u0032 : typeof moduleType\u0032
 >                 : ^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/tests/baselines/reference/functionInIfStatementInModule.js b/tests/baselines/reference/functionInIfStatementInModule.js
index f5f25cc9cdb8c..6afcd6efe7c85 100644
--- a/tests/baselines/reference/functionInIfStatementInModule.js
+++ b/tests/baselines/reference/functionInIfStatementInModule.js
@@ -2,7 +2,7 @@
 
 //// [functionInIfStatementInModule.ts]
  
-module Midori
+namespace Midori
 {
     if (false) {
         function Foo(src)
diff --git a/tests/baselines/reference/functionInIfStatementInModule.symbols b/tests/baselines/reference/functionInIfStatementInModule.symbols
index 96c71570b6914..923b9c0e1ca65 100644
--- a/tests/baselines/reference/functionInIfStatementInModule.symbols
+++ b/tests/baselines/reference/functionInIfStatementInModule.symbols
@@ -2,7 +2,7 @@
 
 === functionInIfStatementInModule.ts ===
  
-module Midori
+namespace Midori
 >Midori : Symbol(Midori, Decl(functionInIfStatementInModule.ts, 0, 0))
 {
     if (false) {
diff --git a/tests/baselines/reference/functionInIfStatementInModule.types b/tests/baselines/reference/functionInIfStatementInModule.types
index 0c2ff67fcbeb0..9910aac2655c6 100644
--- a/tests/baselines/reference/functionInIfStatementInModule.types
+++ b/tests/baselines/reference/functionInIfStatementInModule.types
@@ -2,7 +2,7 @@
 
 === functionInIfStatementInModule.ts ===
  
-module Midori
+namespace Midori
 >Midori : typeof Midori
 >       : ^^^^^^^^^^^^^
 {
diff --git a/tests/baselines/reference/moduleClassArrayCodeGenTest.errors.txt b/tests/baselines/reference/moduleClassArrayCodeGenTest.errors.txt
index d3fe9ca151c49..72adf78dfc2fc 100644
--- a/tests/baselines/reference/moduleClassArrayCodeGenTest.errors.txt
+++ b/tests/baselines/reference/moduleClassArrayCodeGenTest.errors.txt
@@ -4,7 +4,7 @@ moduleClassArrayCodeGenTest.ts(10,11): error TS2694: Namespace 'M' has no export
 ==== moduleClassArrayCodeGenTest.ts (1 errors) ====
     // Invalid code gen for Array of Module class
     
-    module M
+    namespace M
     {
         export class A { }
         class B{ }
diff --git a/tests/baselines/reference/moduleClassArrayCodeGenTest.js b/tests/baselines/reference/moduleClassArrayCodeGenTest.js
index b67a42a03a051..05fa75d326dd2 100644
--- a/tests/baselines/reference/moduleClassArrayCodeGenTest.js
+++ b/tests/baselines/reference/moduleClassArrayCodeGenTest.js
@@ -3,7 +3,7 @@
 //// [moduleClassArrayCodeGenTest.ts]
 // Invalid code gen for Array of Module class
 
-module M
+namespace M
 {
     export class A { }
     class B{ }
diff --git a/tests/baselines/reference/moduleClassArrayCodeGenTest.symbols b/tests/baselines/reference/moduleClassArrayCodeGenTest.symbols
index 0c4e636bc863c..f52f757893297 100644
--- a/tests/baselines/reference/moduleClassArrayCodeGenTest.symbols
+++ b/tests/baselines/reference/moduleClassArrayCodeGenTest.symbols
@@ -3,7 +3,7 @@
 === moduleClassArrayCodeGenTest.ts ===
 // Invalid code gen for Array of Module class
 
-module M
+namespace M
 >M : Symbol(M, Decl(moduleClassArrayCodeGenTest.ts, 0, 0))
 {
     export class A { }
diff --git a/tests/baselines/reference/moduleClassArrayCodeGenTest.types b/tests/baselines/reference/moduleClassArrayCodeGenTest.types
index ced3a0ab7a366..ba377eb9f5a50 100644
--- a/tests/baselines/reference/moduleClassArrayCodeGenTest.types
+++ b/tests/baselines/reference/moduleClassArrayCodeGenTest.types
@@ -3,7 +3,7 @@
 === moduleClassArrayCodeGenTest.ts ===
 // Invalid code gen for Array of Module class
 
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/moduleKeywordDeprecated.errors.txt b/tests/baselines/reference/moduleKeywordDeprecated.errors.txt
new file mode 100644
index 0000000000000..6f1a31c5eb05e
--- /dev/null
+++ b/tests/baselines/reference/moduleKeywordDeprecated.errors.txt
@@ -0,0 +1,58 @@
+decl.d.ts(1,16): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+decl.d.ts(2,16): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+decl.d.ts(2,20): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+decl.d.ts(7,15): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+decl.d.ts(8,15): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+decl.d.ts(8,24): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+foo.ts(2,8): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+foo.ts(3,8): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+foo.ts(3,12): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+foo.ts(4,16): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+foo.ts(5,16): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+foo.ts(5,21): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+
+
+==== foo.ts (6 errors) ====
+    // Error
+    module notok { }
+           ~~~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    module not.ok { }
+           ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+               ~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    declare module bad { }
+                   ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    declare module also.bad { }
+                   ~~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+                        ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    
+    // Still the only way to do it
+    declare module "good" { }
+    
+==== decl.d.ts (6 errors) ====
+    declare module foo { }
+                   ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    declare module foo.bar { }
+                   ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+                       ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    
+    // Still the only way to do it
+    declare module "alsogood" { }
+    
+    export module exported { }
+                  ~~~~~~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    export module exported.sub { }
+                  ~~~~~~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+                           ~~~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleKeywordDeprecated.js b/tests/baselines/reference/moduleKeywordDeprecated.js
new file mode 100644
index 0000000000000..7306e67af7ff8
--- /dev/null
+++ b/tests/baselines/reference/moduleKeywordDeprecated.js
@@ -0,0 +1,24 @@
+//// [tests/cases/compiler/moduleKeywordDeprecated.ts] ////
+
+//// [foo.ts]
+// Error
+module notok { }
+module not.ok { }
+declare module bad { }
+declare module also.bad { }
+
+// Still the only way to do it
+declare module "good" { }
+
+//// [decl.d.ts]
+declare module foo { }
+declare module foo.bar { }
+
+// Still the only way to do it
+declare module "alsogood" { }
+
+export module exported { }
+export module exported.sub { }
+
+
+//// [foo.js]
diff --git a/tests/baselines/reference/moduleKeywordDeprecated.symbols b/tests/baselines/reference/moduleKeywordDeprecated.symbols
new file mode 100644
index 0000000000000..ce5f75431f7b3
--- /dev/null
+++ b/tests/baselines/reference/moduleKeywordDeprecated.symbols
@@ -0,0 +1,41 @@
+//// [tests/cases/compiler/moduleKeywordDeprecated.ts] ////
+
+=== foo.ts ===
+// Error
+module notok { }
+>notok : Symbol(notok, Decl(foo.ts, 0, 0))
+
+module not.ok { }
+>not : Symbol(not, Decl(foo.ts, 1, 16))
+>ok : Symbol(ok, Decl(foo.ts, 2, 11))
+
+declare module bad { }
+>bad : Symbol(bad, Decl(foo.ts, 2, 17))
+
+declare module also.bad { }
+>also : Symbol(also, Decl(foo.ts, 3, 22))
+>bad : Symbol(bad, Decl(foo.ts, 4, 20))
+
+// Still the only way to do it
+declare module "good" { }
+>"good" : Symbol("good", Decl(foo.ts, 4, 27))
+
+=== decl.d.ts ===
+declare module foo { }
+>foo : Symbol(foo, Decl(decl.d.ts, 0, 0), Decl(decl.d.ts, 0, 22))
+
+declare module foo.bar { }
+>foo : Symbol(foo, Decl(decl.d.ts, 0, 0), Decl(decl.d.ts, 0, 22))
+>bar : Symbol(bar, Decl(decl.d.ts, 1, 19))
+
+// Still the only way to do it
+declare module "alsogood" { }
+>"alsogood" : Symbol("alsogood", Decl(decl.d.ts, 1, 26))
+
+export module exported { }
+>exported : Symbol(exported, Decl(decl.d.ts, 4, 29), Decl(decl.d.ts, 6, 26))
+
+export module exported.sub { }
+>exported : Symbol(exported, Decl(decl.d.ts, 4, 29), Decl(decl.d.ts, 6, 26))
+>sub : Symbol(sub, Decl(decl.d.ts, 7, 23))
+
diff --git a/tests/baselines/reference/moduleKeywordDeprecated.types b/tests/baselines/reference/moduleKeywordDeprecated.types
new file mode 100644
index 0000000000000..ac2bdc5fcd7ec
--- /dev/null
+++ b/tests/baselines/reference/moduleKeywordDeprecated.types
@@ -0,0 +1,26 @@
+//// [tests/cases/compiler/moduleKeywordDeprecated.ts] ////
+
+=== foo.ts ===
+// Error
+module notok { }
+module not.ok { }
+declare module bad { }
+declare module also.bad { }
+
+// Still the only way to do it
+declare module "good" { }
+>"good" : typeof import("good")
+>       : ^^^^^^^^^^^^^^^^^^^^^
+
+=== decl.d.ts ===
+declare module foo { }
+declare module foo.bar { }
+
+// Still the only way to do it
+declare module "alsogood" { }
+>"alsogood" : any
+>           : ^^^
+
+export module exported { }
+export module exported.sub { }
+
diff --git a/tests/baselines/reference/moduleMerge.js b/tests/baselines/reference/moduleMerge.js
index ecace8f22c78b..155d1d93c80a0 100644
--- a/tests/baselines/reference/moduleMerge.js
+++ b/tests/baselines/reference/moduleMerge.js
@@ -3,7 +3,7 @@
 //// [moduleMerge.ts]
 // This should not compile both B classes are in the same module this should be a collission
 
-module A
+namespace A
 {
     class B
     {
@@ -14,7 +14,7 @@ module A
     }
 }
 
-module A
+namespace A
 {
     export class B
     {
diff --git a/tests/baselines/reference/moduleMerge.symbols b/tests/baselines/reference/moduleMerge.symbols
index bb06dbe912148..7ff92d181f45b 100644
--- a/tests/baselines/reference/moduleMerge.symbols
+++ b/tests/baselines/reference/moduleMerge.symbols
@@ -3,7 +3,7 @@
 === moduleMerge.ts ===
 // This should not compile both B classes are in the same module this should be a collission
 
-module A
+namespace A
 >A : Symbol(A, Decl(moduleMerge.ts, 0, 0), Decl(moduleMerge.ts, 11, 1))
 {
     class B
@@ -17,7 +17,7 @@ module A
     }
 }
 
-module A
+namespace A
 >A : Symbol(A, Decl(moduleMerge.ts, 0, 0), Decl(moduleMerge.ts, 11, 1))
 {
     export class B
diff --git a/tests/baselines/reference/moduleMerge.types b/tests/baselines/reference/moduleMerge.types
index 8e746a04b5e76..32f5584e7de55 100644
--- a/tests/baselines/reference/moduleMerge.types
+++ b/tests/baselines/reference/moduleMerge.types
@@ -3,7 +3,7 @@
 === moduleMerge.ts ===
 // This should not compile both B classes are in the same module this should be a collission
 
-module A
+namespace A
 >A : typeof A
 >  : ^^^^^^^^
 {
@@ -22,7 +22,7 @@ module A
     }
 }
 
-module A
+namespace A
 >A : typeof A
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/moduleScopingBug.js b/tests/baselines/reference/moduleScopingBug.js
index fbae6fc736971..324a64d1375b4 100644
--- a/tests/baselines/reference/moduleScopingBug.js
+++ b/tests/baselines/reference/moduleScopingBug.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/moduleScopingBug.ts] ////
 
 //// [moduleScopingBug.ts]
-module M
+namespace M
 
 {
 
diff --git a/tests/baselines/reference/moduleScopingBug.symbols b/tests/baselines/reference/moduleScopingBug.symbols
index b744846fd8525..b483474e6d24e 100644
--- a/tests/baselines/reference/moduleScopingBug.symbols
+++ b/tests/baselines/reference/moduleScopingBug.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/moduleScopingBug.ts] ////
 
 === moduleScopingBug.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(moduleScopingBug.ts, 0, 0))
 
 {
diff --git a/tests/baselines/reference/moduleScopingBug.types b/tests/baselines/reference/moduleScopingBug.types
index 4c375677fbdc3..dd11f06a9f4de 100644
--- a/tests/baselines/reference/moduleScopingBug.types
+++ b/tests/baselines/reference/moduleScopingBug.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/moduleScopingBug.ts] ////
 
 === moduleScopingBug.ts ===
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 
diff --git a/tests/baselines/reference/namedFunctionExpressionInModule.js b/tests/baselines/reference/namedFunctionExpressionInModule.js
index e835f55ebc58c..80ca717335350 100644
--- a/tests/baselines/reference/namedFunctionExpressionInModule.js
+++ b/tests/baselines/reference/namedFunctionExpressionInModule.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/namedFunctionExpressionInModule.ts] ////
 
 //// [namedFunctionExpressionInModule.ts]
-module Variables{
+namespace Variables{
     var x = function bar(a, b, c) {
     }
     x(1, 2, 3);
diff --git a/tests/baselines/reference/namedFunctionExpressionInModule.symbols b/tests/baselines/reference/namedFunctionExpressionInModule.symbols
index 7ab00121354d2..9352b8c3960e3 100644
--- a/tests/baselines/reference/namedFunctionExpressionInModule.symbols
+++ b/tests/baselines/reference/namedFunctionExpressionInModule.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/namedFunctionExpressionInModule.ts] ////
 
 === namedFunctionExpressionInModule.ts ===
-module Variables{
+namespace Variables{
 >Variables : Symbol(Variables, Decl(namedFunctionExpressionInModule.ts, 0, 0))
 
     var x = function bar(a, b, c) {
diff --git a/tests/baselines/reference/namedFunctionExpressionInModule.types b/tests/baselines/reference/namedFunctionExpressionInModule.types
index 64f8af41eeeff..455a4b570499c 100644
--- a/tests/baselines/reference/namedFunctionExpressionInModule.types
+++ b/tests/baselines/reference/namedFunctionExpressionInModule.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/namedFunctionExpressionInModule.ts] ////
 
 === namedFunctionExpressionInModule.ts ===
-module Variables{
+namespace Variables{
 >Variables : typeof Variables
 >          : ^^^^^^^^^^^^^^^^
 
diff --git a/tests/baselines/reference/nestedModulePrivateAccess.js b/tests/baselines/reference/nestedModulePrivateAccess.js
index a887bc6d85be9..5e042553ce88a 100644
--- a/tests/baselines/reference/nestedModulePrivateAccess.js
+++ b/tests/baselines/reference/nestedModulePrivateAccess.js
@@ -1,9 +1,9 @@
 //// [tests/cases/compiler/nestedModulePrivateAccess.ts] ////
 
 //// [nestedModulePrivateAccess.ts]
-module a{
+namespace a{
        var x:number;
-       module b{
+       namespace b{
                var y = x; // should not be an error
        }
 }
diff --git a/tests/baselines/reference/nestedModulePrivateAccess.symbols b/tests/baselines/reference/nestedModulePrivateAccess.symbols
index a9f18e367252a..064b67c4e4559 100644
--- a/tests/baselines/reference/nestedModulePrivateAccess.symbols
+++ b/tests/baselines/reference/nestedModulePrivateAccess.symbols
@@ -1,13 +1,13 @@
 //// [tests/cases/compiler/nestedModulePrivateAccess.ts] ////
 
 === nestedModulePrivateAccess.ts ===
-module a{
+namespace a{
 >a : Symbol(a, Decl(nestedModulePrivateAccess.ts, 0, 0))
 
        var x:number;
 >x : Symbol(x, Decl(nestedModulePrivateAccess.ts, 1, 10))
 
-       module b{
+       namespace b{
 >b : Symbol(b, Decl(nestedModulePrivateAccess.ts, 1, 20))
 
                var y = x; // should not be an error
diff --git a/tests/baselines/reference/nestedModulePrivateAccess.types b/tests/baselines/reference/nestedModulePrivateAccess.types
index 5e6b85bc619b3..e3a1cb577308c 100644
--- a/tests/baselines/reference/nestedModulePrivateAccess.types
+++ b/tests/baselines/reference/nestedModulePrivateAccess.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/nestedModulePrivateAccess.ts] ////
 
 === nestedModulePrivateAccess.ts ===
-module a{
+namespace a{
 >a : typeof a
 >  : ^^^^^^^^
 
@@ -9,7 +9,7 @@ module a{
 >x : number
 >  : ^^^^^^
 
-       module b{
+       namespace b{
 >b : typeof b
 >  : ^^^^^^^^
 
diff --git a/tests/baselines/reference/primaryExpressionMods.errors.txt b/tests/baselines/reference/primaryExpressionMods.errors.txt
index 92495911da304..099090c580450 100644
--- a/tests/baselines/reference/primaryExpressionMods.errors.txt
+++ b/tests/baselines/reference/primaryExpressionMods.errors.txt
@@ -3,7 +3,7 @@ primaryExpressionMods.ts(11,8): error TS2833: Cannot find namespace 'm'. Did you
 
 
 ==== primaryExpressionMods.ts (2 errors) ====
-    module M
+    namespace M
     {
         export interface P { x: number; y: number; }
         export var a = 1;
@@ -18,5 +18,5 @@ primaryExpressionMods.ts(11,8): error TS2833: Cannot find namespace 'm'. Did you
     var q: m.P;             // Error
            ~
 !!! error TS2833: Cannot find namespace 'm'. Did you mean 'M'?
-!!! related TS2728 primaryExpressionMods.ts:1:8: 'M' is declared here.
+!!! related TS2728 primaryExpressionMods.ts:1:11: 'M' is declared here.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/primaryExpressionMods.js b/tests/baselines/reference/primaryExpressionMods.js
index b951d8a5a56fd..f30ed1792e3ca 100644
--- a/tests/baselines/reference/primaryExpressionMods.js
+++ b/tests/baselines/reference/primaryExpressionMods.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/primaryExpressionMods.ts] ////
 
 //// [primaryExpressionMods.ts]
-module M
+namespace M
 {
     export interface P { x: number; y: number; }
     export var a = 1;
diff --git a/tests/baselines/reference/primaryExpressionMods.symbols b/tests/baselines/reference/primaryExpressionMods.symbols
index 4f135c0bbd0eb..366f6d92c8c07 100644
--- a/tests/baselines/reference/primaryExpressionMods.symbols
+++ b/tests/baselines/reference/primaryExpressionMods.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/primaryExpressionMods.ts] ////
 
 === primaryExpressionMods.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(primaryExpressionMods.ts, 0, 0))
 {
     export interface P { x: number; y: number; }
diff --git a/tests/baselines/reference/primaryExpressionMods.types b/tests/baselines/reference/primaryExpressionMods.types
index 11cc211066ef1..b19a4422b31eb 100644
--- a/tests/baselines/reference/primaryExpressionMods.types
+++ b/tests/baselines/reference/primaryExpressionMods.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/primaryExpressionMods.ts] ////
 
 === primaryExpressionMods.ts ===
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/project/declareExportAdded/amd/declareExportAdded.errors.txt b/tests/baselines/reference/project/declareExportAdded/amd/declareExportAdded.errors.txt
index 1ca880ef898ef..e524aa4cfe6c4 100644
--- a/tests/baselines/reference/project/declareExportAdded/amd/declareExportAdded.errors.txt
+++ b/tests/baselines/reference/project/declareExportAdded/amd/declareExportAdded.errors.txt
@@ -5,7 +5,7 @@ error TS5107: Option 'moduleResolution=classic' is deprecated and will stop func
 !!! error TS5107: Option 'module=AMD' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'moduleResolution=classic' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ref.d.ts (0 errors) ====
-    declare module M1
+    declare namespace M1
     {
         export function f1(): void;
     }
diff --git a/tests/baselines/reference/project/declareExportAdded/node/declareExportAdded.errors.txt b/tests/baselines/reference/project/declareExportAdded/node/declareExportAdded.errors.txt
index cec554c516db9..e1b346e374150 100644
--- a/tests/baselines/reference/project/declareExportAdded/node/declareExportAdded.errors.txt
+++ b/tests/baselines/reference/project/declareExportAdded/node/declareExportAdded.errors.txt
@@ -3,7 +3,7 @@ error TS5107: Option 'moduleResolution=classic' is deprecated and will stop func
 
 !!! error TS5107: Option 'moduleResolution=classic' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ref.d.ts (0 errors) ====
-    declare module M1
+    declare namespace M1
     {
         export function f1(): void;
     }
diff --git a/tests/baselines/reference/project/declareVariableCollision/amd/declareVariableCollision.errors.txt b/tests/baselines/reference/project/declareVariableCollision/amd/declareVariableCollision.errors.txt
index b1f81b629f7d4..77480e253c19f 100644
--- a/tests/baselines/reference/project/declareVariableCollision/amd/declareVariableCollision.errors.txt
+++ b/tests/baselines/reference/project/declareVariableCollision/amd/declareVariableCollision.errors.txt
@@ -1,20 +1,23 @@
 error TS5107: Option 'module=AMD' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'moduleResolution=classic' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+decl.d.ts(8,19): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
 in1.d.ts(1,8): error TS2300: Duplicate identifier 'a'.
 in2.d.ts(1,8): error TS2300: Duplicate identifier 'a'.
 
 
 !!! error TS5107: Option 'module=AMD' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'moduleResolution=classic' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
-==== decl.d.ts (0 errors) ====
+==== decl.d.ts (1 errors) ====
     // bug 535531: duplicate identifier error reported for "import" declarations in separate files
     
-    declare module A
+    declare namespace A
     {
     
         class MyRoot { }
-    
+        
         export module B
+                      ~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
         {
             class MyClass{ }
         }
diff --git a/tests/baselines/reference/project/declareVariableCollision/node/declareVariableCollision.errors.txt b/tests/baselines/reference/project/declareVariableCollision/node/declareVariableCollision.errors.txt
index a2584e6b97c29..b09fbc8824beb 100644
--- a/tests/baselines/reference/project/declareVariableCollision/node/declareVariableCollision.errors.txt
+++ b/tests/baselines/reference/project/declareVariableCollision/node/declareVariableCollision.errors.txt
@@ -1,18 +1,21 @@
 error TS5107: Option 'moduleResolution=classic' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+decl.d.ts(8,19): error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
 in1.d.ts(1,8): error TS2300: Duplicate identifier 'a'.
 in2.d.ts(1,8): error TS2300: Duplicate identifier 'a'.
 
 
 !!! error TS5107: Option 'moduleResolution=classic' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
-==== decl.d.ts (0 errors) ====
+==== decl.d.ts (1 errors) ====
     // bug 535531: duplicate identifier error reported for "import" declarations in separate files
     
-    declare module A
+    declare namespace A
     {
     
         class MyRoot { }
-    
+        
         export module B
+                      ~
+!!! error TS1540: A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.
         {
             class MyClass{ }
         }
diff --git a/tests/baselines/reference/reachabilityChecks11.errors.txt b/tests/baselines/reference/reachabilityChecks11.errors.txt
index b4497ee46432a..e93449cfa7bb3 100644
--- a/tests/baselines/reference/reachabilityChecks11.errors.txt
+++ b/tests/baselines/reference/reachabilityChecks11.errors.txt
@@ -10,24 +10,24 @@ reachabilityChecks11.ts(69,5): error TS7027: Unreachable code detected.
     // while (true);
     var x = 1;
     
-    module A {
+    namespace A {
         while (true);
         let x;
         ~~~~~~
 !!! error TS7027: Unreachable code detected.
     }
     
-    module A1 {
+    namespace A1 {
         do {} while(true);
-        module A {
+        namespace A {
             interface F {}
         }
     }
     
-    module A2 {
+    namespace A2 {
         while (true);
-        module A {
-        ~~~~~~~~~~
+        namespace A {
+        ~~~~~~~~~~~~~
             var x = 1;
     ~~~~~~~~~~~~~~~~~~
         }
@@ -35,15 +35,15 @@ reachabilityChecks11.ts(69,5): error TS7027: Unreachable code detected.
 !!! error TS7027: Unreachable code detected.
     }
     
-    module A3 {
+    namespace A3 {
         while (true);
         type T = string;
     }
     
-    module A4 {
+    namespace A4 {
         while (true);
-        module A {
-        ~~~~~~~~~~
+        namespace A {
+        ~~~~~~~~~~~~~
             const enum E { X }
     ~~~~~~~~~~~~~~~~~~~~~~~~~~
         }
@@ -70,9 +70,9 @@ reachabilityChecks11.ts(69,5): error TS7027: Unreachable code detected.
 !!! error TS7027: Unreachable code detected.
     }
     
-    module B {
+    namespace B {
         for (; ;);
-        module C {
+        namespace C {
         }
     }
     
diff --git a/tests/baselines/reference/reachabilityChecks11.js b/tests/baselines/reference/reachabilityChecks11.js
index d115e58e816cb..7f0c08492355b 100644
--- a/tests/baselines/reference/reachabilityChecks11.js
+++ b/tests/baselines/reference/reachabilityChecks11.js
@@ -4,33 +4,33 @@
 // while (true);
 var x = 1;
 
-module A {
+namespace A {
     while (true);
     let x;
 }
 
-module A1 {
+namespace A1 {
     do {} while(true);
-    module A {
+    namespace A {
         interface F {}
     }
 }
 
-module A2 {
+namespace A2 {
     while (true);
-    module A {
+    namespace A {
         var x = 1;
     }
 }
 
-module A3 {
+namespace A3 {
     while (true);
     type T = string;
 }
 
-module A4 {
+namespace A4 {
     while (true);
-    module A {
+    namespace A {
         const enum E { X }
     }
 }
@@ -51,9 +51,9 @@ function f2() {
     }
 }
 
-module B {
+namespace B {
     for (; ;);
-    module C {
+    namespace C {
     }
 }
 
diff --git a/tests/baselines/reference/reachabilityChecks11.symbols b/tests/baselines/reference/reachabilityChecks11.symbols
index 450ccad803ff5..bb8868a67c355 100644
--- a/tests/baselines/reference/reachabilityChecks11.symbols
+++ b/tests/baselines/reference/reachabilityChecks11.symbols
@@ -5,7 +5,7 @@
 var x = 1;
 >x : Symbol(x, Decl(reachabilityChecks11.ts, 1, 3))
 
-module A {
+namespace A {
 >A : Symbol(A, Decl(reachabilityChecks11.ts, 1, 10))
 
     while (true);
@@ -13,23 +13,23 @@ module A {
 >x : Symbol(x, Decl(reachabilityChecks11.ts, 5, 7))
 }
 
-module A1 {
+namespace A1 {
 >A1 : Symbol(A1, Decl(reachabilityChecks11.ts, 6, 1))
 
     do {} while(true);
-    module A {
+    namespace A {
 >A : Symbol(A, Decl(reachabilityChecks11.ts, 9, 22))
 
         interface F {}
->F : Symbol(F, Decl(reachabilityChecks11.ts, 10, 14))
+>F : Symbol(F, Decl(reachabilityChecks11.ts, 10, 17))
     }
 }
 
-module A2 {
+namespace A2 {
 >A2 : Symbol(A2, Decl(reachabilityChecks11.ts, 13, 1))
 
     while (true);
-    module A {
+    namespace A {
 >A : Symbol(A, Decl(reachabilityChecks11.ts, 16, 17))
 
         var x = 1;
@@ -37,7 +37,7 @@ module A2 {
     }
 }
 
-module A3 {
+namespace A3 {
 >A3 : Symbol(A3, Decl(reachabilityChecks11.ts, 20, 1))
 
     while (true);
@@ -45,15 +45,15 @@ module A3 {
 >T : Symbol(T, Decl(reachabilityChecks11.ts, 23, 17))
 }
 
-module A4 {
+namespace A4 {
 >A4 : Symbol(A4, Decl(reachabilityChecks11.ts, 25, 1))
 
     while (true);
-    module A {
+    namespace A {
 >A : Symbol(A, Decl(reachabilityChecks11.ts, 28, 17))
 
         const enum E { X }
->E : Symbol(E, Decl(reachabilityChecks11.ts, 29, 14))
+>E : Symbol(E, Decl(reachabilityChecks11.ts, 29, 17))
 >X : Symbol(E.X, Decl(reachabilityChecks11.ts, 30, 22))
     }
 }
@@ -84,11 +84,11 @@ function f2() {
     }
 }
 
-module B {
+namespace B {
 >B : Symbol(B, Decl(reachabilityChecks11.ts, 48, 1))
 
     for (; ;);
-    module C {
+    namespace C {
 >C : Symbol(C, Decl(reachabilityChecks11.ts, 51, 14))
     }
 }
diff --git a/tests/baselines/reference/reachabilityChecks11.types b/tests/baselines/reference/reachabilityChecks11.types
index 49fcc60359573..59400b55e7754 100644
--- a/tests/baselines/reference/reachabilityChecks11.types
+++ b/tests/baselines/reference/reachabilityChecks11.types
@@ -8,7 +8,7 @@ var x = 1;
 >1 : 1
 >  : ^
 
-module A {
+namespace A {
 >A : typeof A
 >  : ^^^^^^^^
 
@@ -21,7 +21,7 @@ module A {
 >  : ^^^
 }
 
-module A1 {
+namespace A1 {
 >A1 : typeof A1
 >   : ^^^^^^^^^
 
@@ -29,12 +29,12 @@ module A1 {
 >true : true
 >     : ^^^^
 
-    module A {
+    namespace A {
         interface F {}
     }
 }
 
-module A2 {
+namespace A2 {
 >A2 : typeof A2
 >   : ^^^^^^^^^
 
@@ -42,7 +42,7 @@ module A2 {
 >true : true
 >     : ^^^^
 
-    module A {
+    namespace A {
 >A : typeof A
 >  : ^^^^^^^^
 
@@ -54,7 +54,7 @@ module A2 {
     }
 }
 
-module A3 {
+namespace A3 {
 >A3 : typeof A3
 >   : ^^^^^^^^^
 
@@ -67,7 +67,7 @@ module A3 {
 >  : ^^^^^^
 }
 
-module A4 {
+namespace A4 {
 >A4 : typeof A4
 >   : ^^^^^^^^^
 
@@ -75,7 +75,7 @@ module A4 {
 >true : true
 >     : ^^^^
 
-    module A {
+    namespace A {
         const enum E { X }
 >E : E
 >  : ^
@@ -121,12 +121,12 @@ function f2() {
     }
 }
 
-module B {
+namespace B {
 >B : typeof B
 >  : ^^^^^^^^
 
     for (; ;);
-    module C {
+    namespace C {
     }
 }
 
diff --git a/tests/baselines/reference/recursiveCloduleReference.js b/tests/baselines/reference/recursiveCloduleReference.js
index 3e53ee61fe4b7..312f4b97b0434 100644
--- a/tests/baselines/reference/recursiveCloduleReference.js
+++ b/tests/baselines/reference/recursiveCloduleReference.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/recursiveCloduleReference.ts] ////
 
 //// [recursiveCloduleReference.ts]
-module M
+namespace M
 {
   export class C {
   }
diff --git a/tests/baselines/reference/recursiveCloduleReference.symbols b/tests/baselines/reference/recursiveCloduleReference.symbols
index cc8546973ada8..51e44627cf578 100644
--- a/tests/baselines/reference/recursiveCloduleReference.symbols
+++ b/tests/baselines/reference/recursiveCloduleReference.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/recursiveCloduleReference.ts] ////
 
 === recursiveCloduleReference.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(recursiveCloduleReference.ts, 0, 0))
 {
   export class C {
diff --git a/tests/baselines/reference/recursiveCloduleReference.types b/tests/baselines/reference/recursiveCloduleReference.types
index 5c879dba45e9f..c257ab04ccb9a 100644
--- a/tests/baselines/reference/recursiveCloduleReference.types
+++ b/tests/baselines/reference/recursiveCloduleReference.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/recursiveCloduleReference.ts] ////
 
 === recursiveCloduleReference.ts ===
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/selfRef.errors.txt b/tests/baselines/reference/selfRef.errors.txt
index 37bdaf9700b52..e4b5edd820f13 100644
--- a/tests/baselines/reference/selfRef.errors.txt
+++ b/tests/baselines/reference/selfRef.errors.txt
@@ -3,7 +3,7 @@ selfRef.ts(12,18): error TS2304: Cannot find name 'name'.
 
 
 ==== selfRef.ts (2 errors) ====
-    module M
+    namespace M
     {
         export class Test
         {
diff --git a/tests/baselines/reference/selfRef.js b/tests/baselines/reference/selfRef.js
index 4ff5e6d6fa118..31a7e338041a8 100644
--- a/tests/baselines/reference/selfRef.js
+++ b/tests/baselines/reference/selfRef.js
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/selfRef.ts] ////
 
 //// [selfRef.ts]
-module M
+namespace M
 {
     export class Test
     {
diff --git a/tests/baselines/reference/selfRef.symbols b/tests/baselines/reference/selfRef.symbols
index 75a9b2457ed21..088fa3304b8b8 100644
--- a/tests/baselines/reference/selfRef.symbols
+++ b/tests/baselines/reference/selfRef.symbols
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/selfRef.ts] ////
 
 === selfRef.ts ===
-module M
+namespace M
 >M : Symbol(M, Decl(selfRef.ts, 0, 0))
 {
     export class Test
diff --git a/tests/baselines/reference/selfRef.types b/tests/baselines/reference/selfRef.types
index adaf914b5348d..c6eddd052ef57 100644
--- a/tests/baselines/reference/selfRef.types
+++ b/tests/baselines/reference/selfRef.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/selfRef.ts] ////
 
 === selfRef.ts ===
-module M
+namespace M
 >M : typeof M
 >  : ^^^^^^^^
 {
diff --git a/tests/baselines/reference/unexportedInstanceClassVariables.js b/tests/baselines/reference/unexportedInstanceClassVariables.js
index d807bcfc3c4f2..ef47f868403fa 100644
--- a/tests/baselines/reference/unexportedInstanceClassVariables.js
+++ b/tests/baselines/reference/unexportedInstanceClassVariables.js
@@ -1,13 +1,13 @@
 //// [tests/cases/compiler/unexportedInstanceClassVariables.ts] ////
 
 //// [unexportedInstanceClassVariables.ts]
-module M{
+namespace M{
 	class A{
 		constructor(val:string){}
 	}
 }
 
-module M{
+namespace M{
 	class A {}  
  
  	var a = new A();
diff --git a/tests/baselines/reference/unexportedInstanceClassVariables.symbols b/tests/baselines/reference/unexportedInstanceClassVariables.symbols
index 22099e203d41f..2984600d95964 100644
--- a/tests/baselines/reference/unexportedInstanceClassVariables.symbols
+++ b/tests/baselines/reference/unexportedInstanceClassVariables.symbols
@@ -1,25 +1,25 @@
 //// [tests/cases/compiler/unexportedInstanceClassVariables.ts] ////
 
 === unexportedInstanceClassVariables.ts ===
-module M{
+namespace M{
 >M : Symbol(M, Decl(unexportedInstanceClassVariables.ts, 0, 0), Decl(unexportedInstanceClassVariables.ts, 4, 1))
 
 	class A{
->A : Symbol(A, Decl(unexportedInstanceClassVariables.ts, 0, 9))
+>A : Symbol(A, Decl(unexportedInstanceClassVariables.ts, 0, 12))
 
 		constructor(val:string){}
 >val : Symbol(val, Decl(unexportedInstanceClassVariables.ts, 2, 14))
 	}
 }
 
-module M{
+namespace M{
 >M : Symbol(M, Decl(unexportedInstanceClassVariables.ts, 0, 0), Decl(unexportedInstanceClassVariables.ts, 4, 1))
 
 	class A {}  
->A : Symbol(A, Decl(unexportedInstanceClassVariables.ts, 6, 9))
+>A : Symbol(A, Decl(unexportedInstanceClassVariables.ts, 6, 12))
  
  	var a = new A();
 >a : Symbol(a, Decl(unexportedInstanceClassVariables.ts, 9, 5))
->A : Symbol(A, Decl(unexportedInstanceClassVariables.ts, 6, 9))
+>A : Symbol(A, Decl(unexportedInstanceClassVariables.ts, 6, 12))
 }
 
diff --git a/tests/baselines/reference/unexportedInstanceClassVariables.types b/tests/baselines/reference/unexportedInstanceClassVariables.types
index 1377e17dc10a2..4457806b25916 100644
--- a/tests/baselines/reference/unexportedInstanceClassVariables.types
+++ b/tests/baselines/reference/unexportedInstanceClassVariables.types
@@ -1,7 +1,7 @@
 //// [tests/cases/compiler/unexportedInstanceClassVariables.ts] ////
 
 === unexportedInstanceClassVariables.ts ===
-module M{
+namespace M{
 >M : typeof M
 >  : ^^^^^^^^
 
@@ -15,7 +15,7 @@ module M{
 	}
 }
 
-module M{
+namespace M{
 >M : typeof M
 >  : ^^^^^^^^
 
diff --git a/tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts b/tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts
index fed9cc82e5ef5..3cb995ad8adfa 100644
--- a/tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts
+++ b/tests/cases/compiler/cannotInvokeNewOnErrorExpression.ts
@@ -1,4 +1,4 @@
-module M
+namespace M
 {
     class ClassA {}
 }
diff --git a/tests/cases/compiler/circularModuleImports.ts b/tests/cases/compiler/circularModuleImports.ts
index b251eab3335c3..af948e57f36a0 100644
--- a/tests/cases/compiler/circularModuleImports.ts
+++ b/tests/cases/compiler/circularModuleImports.ts
@@ -1,4 +1,4 @@
-module M
+namespace M
  
 {
  
diff --git a/tests/cases/compiler/cloduleTest1.ts b/tests/cases/compiler/cloduleTest1.ts
index d5bc88b42de49..e844b5b843e36 100644
--- a/tests/cases/compiler/cloduleTest1.ts
+++ b/tests/cases/compiler/cloduleTest1.ts
@@ -2,7 +2,7 @@
   interface $ {
       addClass(className: string): $;
   }
-  module $ {
+  namespace $ {
     export interface AjaxSettings {
     }
     export function ajax(options: AjaxSettings) { }
diff --git a/tests/cases/compiler/cloduleWithRecursiveReference.ts b/tests/cases/compiler/cloduleWithRecursiveReference.ts
index 47f94f8b1c052..0a01dc87abbba 100644
--- a/tests/cases/compiler/cloduleWithRecursiveReference.ts
+++ b/tests/cases/compiler/cloduleWithRecursiveReference.ts
@@ -1,4 +1,4 @@
-module M
+namespace M
 {
   export class C {  }
   export namespace C {
diff --git a/tests/cases/compiler/declareDottedExtend.ts b/tests/cases/compiler/declareDottedExtend.ts
index 2ee2086cb3a03..462bca45cad5d 100644
--- a/tests/cases/compiler/declareDottedExtend.ts
+++ b/tests/cases/compiler/declareDottedExtend.ts
@@ -1,4 +1,4 @@
-declare module A.B
+declare namespace A.B
 {
     export class C{ }
 }
diff --git a/tests/cases/compiler/dottedModuleName2.ts b/tests/cases/compiler/dottedModuleName2.ts
index ece392a9ed1cd..a68e65c6c1640 100644
--- a/tests/cases/compiler/dottedModuleName2.ts
+++ b/tests/cases/compiler/dottedModuleName2.ts
@@ -19,7 +19,7 @@ var tmpOK = AA.B.x;
 var tmpError = A.B.x;
 
 
-module A.B.C
+namespace A.B.C
  
 {
  
@@ -29,7 +29,7 @@ module A.B.C
  
  
  
-module M
+namespace M
  
 {
  
diff --git a/tests/cases/compiler/escapedIdentifiers.ts b/tests/cases/compiler/escapedIdentifiers.ts
index c220bd1932098..76f3632f7cba7 100644
--- a/tests/cases/compiler/escapedIdentifiers.ts
+++ b/tests/cases/compiler/escapedIdentifiers.ts
@@ -25,7 +25,7 @@ b ++;
 namespace moduleType1 { 
     export var baz1: number;
 }
-module moduleType\u0032 { 
+declare module moduleType\u0032 { 
     export var baz2: number;
 }
 
diff --git a/tests/cases/compiler/functionInIfStatementInModule.ts b/tests/cases/compiler/functionInIfStatementInModule.ts
index 1bb53ee9b19cf..485928b0b9892 100644
--- a/tests/cases/compiler/functionInIfStatementInModule.ts
+++ b/tests/cases/compiler/functionInIfStatementInModule.ts
@@ -1,5 +1,5 @@
  
-module Midori
+namespace Midori
 {
     if (false) {
         function Foo(src)
diff --git a/tests/cases/compiler/moduleClassArrayCodeGenTest.ts b/tests/cases/compiler/moduleClassArrayCodeGenTest.ts
index 3d30b9a9fa821..07a9b8dd7c260 100644
--- a/tests/cases/compiler/moduleClassArrayCodeGenTest.ts
+++ b/tests/cases/compiler/moduleClassArrayCodeGenTest.ts
@@ -1,6 +1,6 @@
 // Invalid code gen for Array of Module class
 
-module M
+namespace M
 {
     export class A { }
     class B{ }
diff --git a/tests/cases/compiler/moduleKeywordDeprecated.ts b/tests/cases/compiler/moduleKeywordDeprecated.ts
new file mode 100644
index 0000000000000..08c5c0c94cb14
--- /dev/null
+++ b/tests/cases/compiler/moduleKeywordDeprecated.ts
@@ -0,0 +1,21 @@
+// @filename: foo.ts
+
+// Error
+module notok { }
+module not.ok { }
+declare module bad { }
+declare module also.bad { }
+
+// Still the only way to do it
+declare module "good" { }
+
+// @filename: decl.d.ts
+
+declare module foo { }
+declare module foo.bar { }
+
+// Still the only way to do it
+declare module "alsogood" { }
+
+export module exported { }
+export module exported.sub { }
diff --git a/tests/cases/compiler/moduleMerge.ts b/tests/cases/compiler/moduleMerge.ts
index 94ca217fc115e..de1ae22d58106 100644
--- a/tests/cases/compiler/moduleMerge.ts
+++ b/tests/cases/compiler/moduleMerge.ts
@@ -1,6 +1,6 @@
 // This should not compile both B classes are in the same module this should be a collission
 
-module A
+namespace A
 {
     class B
     {
@@ -11,7 +11,7 @@ module A
     }
 }
 
-module A
+namespace A
 {
     export class B
     {
diff --git a/tests/cases/compiler/moduleScopingBug.ts b/tests/cases/compiler/moduleScopingBug.ts
index 53f0f7c84c251..3b33be8e18324 100644
--- a/tests/cases/compiler/moduleScopingBug.ts
+++ b/tests/cases/compiler/moduleScopingBug.ts
@@ -1,4 +1,4 @@
-module M
+namespace M
 
 {
 
diff --git a/tests/cases/compiler/namedFunctionExpressionInModule.ts b/tests/cases/compiler/namedFunctionExpressionInModule.ts
index 66a6b7a545edc..f4da02d6ad273 100644
--- a/tests/cases/compiler/namedFunctionExpressionInModule.ts
+++ b/tests/cases/compiler/namedFunctionExpressionInModule.ts
@@ -1,4 +1,4 @@
-module Variables{
+namespace Variables{
     var x = function bar(a, b, c) {
     }
     x(1, 2, 3);
diff --git a/tests/cases/compiler/nestedModulePrivateAccess.ts b/tests/cases/compiler/nestedModulePrivateAccess.ts
index 6770321fd4685..7625d4b8af074 100644
--- a/tests/cases/compiler/nestedModulePrivateAccess.ts
+++ b/tests/cases/compiler/nestedModulePrivateAccess.ts
@@ -1,6 +1,6 @@
-module a{
+namespace a{
        var x:number;
-       module b{
+       namespace b{
                var y = x; // should not be an error
        }
 }
\ No newline at end of file
diff --git a/tests/cases/compiler/primaryExpressionMods.ts b/tests/cases/compiler/primaryExpressionMods.ts
index 7474d8b1e36d0..a0c571435f498 100644
--- a/tests/cases/compiler/primaryExpressionMods.ts
+++ b/tests/cases/compiler/primaryExpressionMods.ts
@@ -1,4 +1,4 @@
-module M
+namespace M
 {
     export interface P { x: number; y: number; }
     export var a = 1;
diff --git a/tests/cases/compiler/reachabilityChecks11.ts b/tests/cases/compiler/reachabilityChecks11.ts
index 81dbcf3c7ad81..abcafb411331a 100644
--- a/tests/cases/compiler/reachabilityChecks11.ts
+++ b/tests/cases/compiler/reachabilityChecks11.ts
@@ -4,33 +4,33 @@
 // while (true);
 var x = 1;
 
-module A {
+namespace A {
     while (true);
     let x;
 }
 
-module A1 {
+namespace A1 {
     do {} while(true);
-    module A {
+    namespace A {
         interface F {}
     }
 }
 
-module A2 {
+namespace A2 {
     while (true);
-    module A {
+    namespace A {
         var x = 1;
     }
 }
 
-module A3 {
+namespace A3 {
     while (true);
     type T = string;
 }
 
-module A4 {
+namespace A4 {
     while (true);
-    module A {
+    namespace A {
         const enum E { X }
     }
 }
@@ -51,9 +51,9 @@ function f2() {
     }
 }
 
-module B {
+namespace B {
     for (; ;);
-    module C {
+    namespace C {
     }
 }
 
diff --git a/tests/cases/compiler/recursiveCloduleReference.ts b/tests/cases/compiler/recursiveCloduleReference.ts
index b2745b7cb60b2..d54c1a92935ce 100644
--- a/tests/cases/compiler/recursiveCloduleReference.ts
+++ b/tests/cases/compiler/recursiveCloduleReference.ts
@@ -1,4 +1,4 @@
-module M
+namespace M
 {
   export class C {
   }
diff --git a/tests/cases/compiler/selfRef.ts b/tests/cases/compiler/selfRef.ts
index 1f8a079789c71..1dd2b09907ebd 100644
--- a/tests/cases/compiler/selfRef.ts
+++ b/tests/cases/compiler/selfRef.ts
@@ -1,5 +1,5 @@
 // @lib: es5
-module M
+namespace M
 {
     export class Test
     {
diff --git a/tests/cases/compiler/unexportedInstanceClassVariables.ts b/tests/cases/compiler/unexportedInstanceClassVariables.ts
index 1a45b5c0211f0..1d09e27b67638 100644
--- a/tests/cases/compiler/unexportedInstanceClassVariables.ts
+++ b/tests/cases/compiler/unexportedInstanceClassVariables.ts
@@ -1,10 +1,10 @@
-module M{
+namespace M{
 	class A{
 		constructor(val:string){}
 	}
 }
 
-module M{
+namespace M{
 	class A {}  
  
  	var a = new A();
diff --git a/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts b/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts
index 2e09672ed4278..edd23b90d3ce5 100644
--- a/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts
+++ b/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedClassesOfTheSameName.ts
@@ -5,7 +5,7 @@ namespace A {
     }
 }
 
-module A{
+namespace A{
     // expected error
     export class Point {
         origin: number;
diff --git a/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts b/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts
index 734f65b0c563d..fe49116404e89 100644
--- a/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts
+++ b/tests/cases/conformance/internalModules/DeclarationMerging/TwoInternalModulesThatMergeEachWithExportedModulesOfTheSameName.ts
@@ -2,7 +2,7 @@ namespace A.B {
     export var x: number;
 }
 
-module A{ 
+namespace A{ 
     namespace B {
         export var x: string;
     }
diff --git a/tests/cases/fourslash/moduleDeclarationDeprecated_suggestion1.ts b/tests/cases/fourslash/moduleDeclarationDeprecated_suggestion1.ts
deleted file mode 100644
index 5554300a5a0b9..0000000000000
--- a/tests/cases/fourslash/moduleDeclarationDeprecated_suggestion1.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-///<reference path="fourslash.ts" />
-// @Filename: a.ts
-////[|module|] mod1 { export let x: number }
-////declare [|module|] mod2 { export let x: number }
-////export [|module|] mod3 { export let x: number }
-////export declare [|module|] mod4 { export let x: number }
-////namespace mod5 { export let x: number }
-////declare namespace mod6 { export let x: number }
-////declare module "module-augmentation" {}
-////declare global {}
-////mod1.x = 1;
-////mod2.x = 1;
-////mod5.x = 1;
-////mod6.x = 1;
-
-// @Filename: b.ts
-////module "global-ambient-module" {}
-
-goTo.file("a.ts")
-const diagnostics = test.ranges().map(range => ({
-    code: 1540,
-    message: "A 'namespace' declaration should not be declared using the 'module' keyword. Please use the 'namespace' keyword instead.",
-    reportsDeprecated: true,
-    range,
-}));
-verify.getSuggestionDiagnostics(diagnostics)
-
-goTo.file("b.ts")
-verify.getSuggestionDiagnostics([])
-
diff --git a/tests/cases/fourslash/moduleDeclarationDeprecated_suggestion2.ts b/tests/cases/fourslash/moduleDeclarationDeprecated_suggestion2.ts
deleted file mode 100644
index f592302417d0b..0000000000000
--- a/tests/cases/fourslash/moduleDeclarationDeprecated_suggestion2.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-///<reference path="fourslash.ts" />
-// @Filename: a.ts
-////declare module
-
-const ranges = test.ranges();
-verify.getSuggestionDiagnostics([])
diff --git a/tests/cases/projects/DeclareExportAdded/ref.d.ts b/tests/cases/projects/DeclareExportAdded/ref.d.ts
index 4ce3adee420c0..242a4eb2e7b8e 100644
--- a/tests/cases/projects/DeclareExportAdded/ref.d.ts
+++ b/tests/cases/projects/DeclareExportAdded/ref.d.ts
@@ -1,4 +1,4 @@
-declare module M1
+declare namespace M1
 {
     export function f1(): void;
 }
\ No newline at end of file
diff --git a/tests/cases/projects/declareVariableCollision/decl.d.ts b/tests/cases/projects/declareVariableCollision/decl.d.ts
index 9bcb7bb84b436..69a141268cda7 100644
--- a/tests/cases/projects/declareVariableCollision/decl.d.ts
+++ b/tests/cases/projects/declareVariableCollision/decl.d.ts
@@ -1,10 +1,10 @@
 // bug 535531: duplicate identifier error reported for "import" declarations in separate files
 
-declare module A
+declare namespace A
 {
 
     class MyRoot { }
-
+    
     export module B
     {
         class MyClass{ }