diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 173ffcb8fee..de3d8fde307 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14289,8 +14289,9 @@ namespace ts {
                         }
                     }
                     break;
+                case SyntaxKind.ExportAssignment:
                 case SyntaxKind.ExportDeclaration:
-                    grammarErrorOnFirstToken(node, Diagnostics.Exports_are_not_permitted_in_module_augmentations);
+                    grammarErrorOnFirstToken(node, Diagnostics.Exports_and_export_assignments_are_not_permitted_in_module_augmentations);
                     break;
                 case SyntaxKind.ImportEqualsDeclaration:
                     if ((<ImportEqualsDeclaration>node).moduleReference.kind !== SyntaxKind.StringLiteral) {
@@ -14564,7 +14565,9 @@ namespace ts {
                 const exportEqualsSymbol = moduleSymbol.exports["export="];
                 if (exportEqualsSymbol && hasExportedMembers(moduleSymbol)) {
                     const declaration = getDeclarationOfAliasSymbol(exportEqualsSymbol) || exportEqualsSymbol.valueDeclaration;
-                    error(declaration, Diagnostics.An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements);
+                    if (!isTopLevelInExternalModuleAugmentation(declaration)) {
+                        error(declaration, Diagnostics.An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements);
+                    }
                 }
                 // Checks for export * conflicts
                 const exports = getExportsOfModule(moduleSymbol);
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index fff6f75d20d..2ffaccec7f0 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1783,7 +1783,7 @@
         "category": "Error",
         "code": 2663
     },
-    "Exports are not permitted in module augmentations.": {
+    "Exports and export assignments are not permitted in module augmentations.": {
         "category": "Error",
         "code": 2664
     },
diff --git a/tests/baselines/reference/globalIsContextualKeyword.js b/tests/baselines/reference/globalIsContextualKeyword.js
new file mode 100644
index 00000000000..b6fa566c91a
--- /dev/null
+++ b/tests/baselines/reference/globalIsContextualKeyword.js
@@ -0,0 +1,34 @@
+//// [globalIsContextualKeyword.ts]
+function a() {
+    let global = 1;
+}
+function b() {
+    class global {}
+}
+
+namespace global {
+}
+
+function foo(global: number) {
+}
+
+let obj = {
+    global: "123"
+}
+
+//// [globalIsContextualKeyword.js]
+function a() {
+    var global = 1;
+}
+function b() {
+    var global = (function () {
+        function global() {
+        }
+        return global;
+    }());
+}
+function foo(global) {
+}
+var obj = {
+    global: "123"
+};
diff --git a/tests/baselines/reference/globalIsContextualKeyword.symbols b/tests/baselines/reference/globalIsContextualKeyword.symbols
new file mode 100644
index 00000000000..edc1cebbc95
--- /dev/null
+++ b/tests/baselines/reference/globalIsContextualKeyword.symbols
@@ -0,0 +1,29 @@
+=== tests/cases/compiler/globalIsContextualKeyword.ts ===
+function a() {
+>a : Symbol(a, Decl(globalIsContextualKeyword.ts, 0, 0))
+
+    let global = 1;
+>global : Symbol(global, Decl(globalIsContextualKeyword.ts, 1, 7))
+}
+function b() {
+>b : Symbol(b, Decl(globalIsContextualKeyword.ts, 2, 1))
+
+    class global {}
+>global : Symbol(global, Decl(globalIsContextualKeyword.ts, 3, 14))
+}
+
+namespace global {
+>global : Symbol(global, Decl(globalIsContextualKeyword.ts, 5, 1))
+}
+
+function foo(global: number) {
+>foo : Symbol(foo, Decl(globalIsContextualKeyword.ts, 8, 1))
+>global : Symbol(global, Decl(globalIsContextualKeyword.ts, 10, 13))
+}
+
+let obj = {
+>obj : Symbol(obj, Decl(globalIsContextualKeyword.ts, 13, 3))
+
+    global: "123"
+>global : Symbol(global, Decl(globalIsContextualKeyword.ts, 13, 11))
+}
diff --git a/tests/baselines/reference/globalIsContextualKeyword.types b/tests/baselines/reference/globalIsContextualKeyword.types
new file mode 100644
index 00000000000..d0bf624af6d
--- /dev/null
+++ b/tests/baselines/reference/globalIsContextualKeyword.types
@@ -0,0 +1,32 @@
+=== tests/cases/compiler/globalIsContextualKeyword.ts ===
+function a() {
+>a : () => void
+
+    let global = 1;
+>global : number
+>1 : number
+}
+function b() {
+>b : () => void
+
+    class global {}
+>global : global
+}
+
+namespace global {
+>global : any
+}
+
+function foo(global: number) {
+>foo : (global: number) => void
+>global : number
+}
+
+let obj = {
+>obj : { global: string; }
+>{    global: "123"} : { global: string; }
+
+    global: "123"
+>global : string
+>"123" : string
+}
diff --git a/tests/baselines/reference/moduleAugmentationDisallowedExtensions.errors.txt b/tests/baselines/reference/moduleAugmentationDisallowedExtensions.errors.txt
index b4ca1bfa667..f90b07dd815 100644
--- a/tests/baselines/reference/moduleAugmentationDisallowedExtensions.errors.txt
+++ b/tests/baselines/reference/moduleAugmentationDisallowedExtensions.errors.txt
@@ -12,17 +12,18 @@ tests/cases/compiler/x.ts(18,5): error TS2665: Imports are not permitted in modu
 tests/cases/compiler/x.ts(18,26): error TS2307: Cannot find module './x0'.
 tests/cases/compiler/x.ts(19,5): error TS2665: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
 tests/cases/compiler/x.ts(19,21): error TS2307: Cannot find module './x0'.
-tests/cases/compiler/x.ts(20,5): error TS2664: Exports are not permitted in module augmentations.
+tests/cases/compiler/x.ts(20,5): error TS2664: Exports and export assignments are not permitted in module augmentations.
 tests/cases/compiler/x.ts(20,19): error TS2307: Cannot find module './x0'.
-tests/cases/compiler/x.ts(21,5): error TS2664: Exports are not permitted in module augmentations.
+tests/cases/compiler/x.ts(21,5): error TS2664: Exports and export assignments are not permitted in module augmentations.
 tests/cases/compiler/x.ts(21,21): error TS2307: Cannot find module './x0'.
+tests/cases/compiler/x.ts(25,5): error TS2664: Exports and export assignments are not permitted in module augmentations.
 
 
 ==== tests/cases/compiler/x0.ts (0 errors) ====
     
     export let a = 1;
     
-==== tests/cases/compiler/x.ts (18 errors) ====
+==== tests/cases/compiler/x.ts (19 errors) ====
     
     namespace N1 {
         export let x = 1;
@@ -72,15 +73,21 @@ tests/cases/compiler/x.ts(21,21): error TS2307: Cannot find module './x0'.
 !!! error TS2307: Cannot find module './x0'.
         export * from "./x0";
         ~~~~~~
-!!! error TS2664: Exports are not permitted in module augmentations.
+!!! error TS2664: Exports and export assignments are not permitted in module augmentations.
                       ~~~~~~
 !!! error TS2307: Cannot find module './x0'.
         export {a} from "./x0";
         ~~~~~~
-!!! error TS2664: Exports are not permitted in module augmentations.
+!!! error TS2664: Exports and export assignments are not permitted in module augmentations.
                         ~~~~~~
 !!! error TS2307: Cannot find module './x0'.
     }
+    
+    declare module "./test" {
+        export = N1;
+        ~~~~~~
+!!! error TS2664: Exports and export assignments are not permitted in module augmentations.
+    }
     export {}
     
 ==== tests/cases/compiler/observable.ts (0 errors) ====
@@ -89,6 +96,9 @@ tests/cases/compiler/x.ts(21,21): error TS2307: Cannot find module './x0'.
     }
     export var x = 1;
     
+==== tests/cases/compiler/test.ts (0 errors) ====
+    export let b = 1;
+    
 ==== tests/cases/compiler/main.ts (0 errors) ====
     import { Observable } from "./observable"
     import "./x";
diff --git a/tests/baselines/reference/moduleAugmentationDisallowedExtensions.js b/tests/baselines/reference/moduleAugmentationDisallowedExtensions.js
index f5378b7c5bd..62b14d71277 100644
--- a/tests/baselines/reference/moduleAugmentationDisallowedExtensions.js
+++ b/tests/baselines/reference/moduleAugmentationDisallowedExtensions.js
@@ -27,6 +27,10 @@ declare module "./observable" {
     export * from "./x0";
     export {a} from "./x0";
 }
+
+declare module "./test" {
+    export = N1;
+}
 export {}
 
 //// [observable.ts]
@@ -35,6 +39,9 @@ export declare class Observable<T> {
 }
 export var x = 1;
 
+//// [test.ts]
+export let b = 1;
+
 //// [main.ts]
 import { Observable } from "./observable"
 import "./x";
@@ -52,6 +59,9 @@ var N1;
 //// [observable.js]
 "use strict";
 exports.x = 1;
+//// [test.js]
+"use strict";
+exports.b = 1;
 //// [main.js]
 "use strict";
 require("./x");
diff --git a/tests/baselines/reference/moduleAugmentationImportsAndExports2.errors.txt b/tests/baselines/reference/moduleAugmentationImportsAndExports2.errors.txt
index 360c89080a9..95bd0a714e0 100644
--- a/tests/baselines/reference/moduleAugmentationImportsAndExports2.errors.txt
+++ b/tests/baselines/reference/moduleAugmentationImportsAndExports2.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/compiler/f3.ts(11,5): error TS2665: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
 tests/cases/compiler/f3.ts(11,21): error TS2307: Cannot find module './f2'.
-tests/cases/compiler/f3.ts(12,5): error TS2664: Exports are not permitted in module augmentations.
+tests/cases/compiler/f3.ts(12,5): error TS2664: Exports and export assignments are not permitted in module augmentations.
 tests/cases/compiler/f3.ts(12,21): error TS2307: Cannot find module './f2'.
 tests/cases/compiler/f3.ts(13,12): error TS2663: Module augmentation cannot introduce new names in the top level scope.
 tests/cases/compiler/f3.ts(13,16): error TS4000: Import declaration 'I' is using private name 'N'.
@@ -37,7 +37,7 @@ tests/cases/compiler/f4.ts(5,11): error TS2339: Property 'foo' does not exist on
 !!! error TS2307: Cannot find module './f2'.
         export {B} from "./f2";
         ~~~~~~
-!!! error TS2664: Exports are not permitted in module augmentations.
+!!! error TS2664: Exports and export assignments are not permitted in module augmentations.
                         ~~~~~~
 !!! error TS2307: Cannot find module './f2'.
         import I = N.Ifc;
diff --git a/tests/cases/compiler/globalIsContextualKeyword.ts b/tests/cases/compiler/globalIsContextualKeyword.ts
new file mode 100644
index 00000000000..ceae834a267
--- /dev/null
+++ b/tests/cases/compiler/globalIsContextualKeyword.ts
@@ -0,0 +1,16 @@
+function a() {
+    let global = 1;
+}
+function b() {
+    class global {}
+}
+
+namespace global {
+}
+
+function foo(global: number) {
+}
+
+let obj = {
+    global: "123"
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/moduleAugmentationDisallowedExtensions.ts b/tests/cases/compiler/moduleAugmentationDisallowedExtensions.ts
index 28e46c71b33..116c5cb7820 100644
--- a/tests/cases/compiler/moduleAugmentationDisallowedExtensions.ts
+++ b/tests/cases/compiler/moduleAugmentationDisallowedExtensions.ts
@@ -26,6 +26,10 @@ declare module "./observable" {
     export * from "./x0";
     export {a} from "./x0";
 }
+
+declare module "./test" {
+    export = N1;
+}
 export {}
 
 // @filename: observable.ts
@@ -34,6 +38,9 @@ export declare class Observable<T> {
 }
 export var x = 1;
 
+// @filename: test.ts
+export let b = 1;
+
 // @filename: main.ts
 import { Observable } from "./observable"
 import "./x";