diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 1ad31795beb..828ddb0dec0 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11114,6 +11114,14 @@ module ts {
         function checkModuleDeclaration(node: ModuleDeclaration) {
             if (produceDiagnostics) {
                 // Grammar checking
+                let isAmbientExternalModule = node.name.kind === SyntaxKind.StringLiteral;
+                let contextErrorMessage = isAmbientExternalModule
+                    ? Diagnostics.An_ambient_module_declaration_is_only_allowed_at_the_top_level_in_a_file
+                    : Diagnostics.A_namespace_declaration_is_only_allowed_in_a_namespace_or_module;
+                if (!checkGrammarModuleElementContext(node, contextErrorMessage)) {
+                    return;
+                }
+
                 if (!checkGrammarDeclarationNameInStrictMode(node) && !checkGrammarDecorators(node) && !checkGrammarModifiers(node)) {
                     if (!isInAmbientContext(node) && node.name.kind === SyntaxKind.StringLiteral) {
                         grammarErrorOnNode(node.name, Diagnostics.Only_ambient_modules_can_use_quoted_names);
@@ -11150,7 +11158,7 @@ module ts {
                 }
 
                 // Checks for ambient external modules.
-                if (node.name.kind === SyntaxKind.StringLiteral) {
+                if (isAmbientExternalModule) {
                     if (!isGlobalSourceFile(node.parent)) {
                         error(node.name, Diagnostics.Ambient_modules_cannot_be_nested_in_other_modules);
                     }
@@ -11227,6 +11235,9 @@ module ts {
         }
 
         function checkImportDeclaration(node: ImportDeclaration) {
+            if (!checkGrammarModuleElementContext(node, Diagnostics.An_import_declaration_can_only_be_used_in_a_namespace_or_module)) {
+                return;
+            }
             if (!checkGrammarImportDeclarationNameInStrictMode(node) && !checkGrammarDecorators(node) && !checkGrammarModifiers(node) && (node.flags & NodeFlags.Modifier)) {
                 grammarErrorOnFirstToken(node, Diagnostics.An_import_declaration_cannot_have_modifiers);
             }
@@ -11249,6 +11260,10 @@ module ts {
         }
 
         function checkImportEqualsDeclaration(node: ImportEqualsDeclaration) {
+            if (!checkGrammarModuleElementContext(node, Diagnostics.An_import_declaration_can_only_be_used_in_a_namespace_or_module)) {
+                return;
+            }
+
             checkGrammarDeclarationNameInStrictMode(node) || checkGrammarDecorators(node) || checkGrammarModifiers(node);
             if (isInternalModuleImportEqualsDeclaration(node) || checkExternalImportOrExportDeclaration(node)) {
                 checkImportBinding(node);
@@ -11280,9 +11295,14 @@ module ts {
         }
 
         function checkExportDeclaration(node: ExportDeclaration) {
+            if (!checkGrammarModuleElementContext(node, Diagnostics.An_export_declaration_can_only_be_used_in_a_module)) {
+                return;
+            }
+
             if (!checkGrammarDecorators(node) && !checkGrammarModifiers(node) && (node.flags & NodeFlags.Modifier)) {
                 grammarErrorOnFirstToken(node, Diagnostics.An_export_declaration_cannot_have_modifiers);
             }
+
             if (!node.moduleSpecifier || checkExternalImportOrExportDeclaration(node)) {
                 if (node.exportClause) {
                     // export { x, y }
@@ -11304,6 +11324,15 @@ module ts {
             }
         }
 
+        function checkGrammarModuleElementContext(node: ModuleElement, errorMessage: DiagnosticMessage): boolean {
+            if (node.parent.kind !== SyntaxKind.SourceFile && node.parent.kind !== SyntaxKind.ModuleBlock && node.parent.kind !== SyntaxKind.ModuleDeclaration) {
+                grammarErrorOnFirstToken(node, errorMessage);
+                return false;
+            }
+
+            return true;
+        }
+
         function checkExportSpecifier(node: ExportSpecifier) {
             checkAliasSymbol(node);
             if (!(<ExportDeclaration>node.parent.parent).moduleSpecifier) {
@@ -11312,8 +11341,7 @@ module ts {
         }
 
         function checkExportAssignment(node: ExportAssignment) {
-            if (node.parent.kind !== SyntaxKind.SourceFile && node.parent.kind !== SyntaxKind.ModuleBlock) {
-                // TODO: StatementFlags
+            if (!checkGrammarModuleElementContext(node, Diagnostics.An_export_assignment_can_only_be_used_in_a_module)) {
                 return;
             }
 
diff --git a/src/compiler/diagnosticInformationMap.generated.ts b/src/compiler/diagnosticInformationMap.generated.ts
index 0c8be2d3c54..9f6190ead11 100644
--- a/src/compiler/diagnosticInformationMap.generated.ts
+++ b/src/compiler/diagnosticInformationMap.generated.ts
@@ -186,6 +186,11 @@ module ts {
         A_type_predicate_is_only_allowed_in_return_type_position_for_functions_and_methods: { code: 1228, category: DiagnosticCategory.Error, key: "A type predicate is only allowed in return type position for functions and methods." },
         A_type_predicate_cannot_reference_a_rest_parameter: { code: 1229, category: DiagnosticCategory.Error, key: "A type predicate cannot reference a rest parameter." },
         A_type_predicate_cannot_reference_element_0_in_a_binding_pattern: { code: 1230, category: DiagnosticCategory.Error, key: "A type predicate cannot reference element '{0}' in a binding pattern." },
+        An_export_assignment_can_only_be_used_in_a_module: { code: 1231, category: DiagnosticCategory.Error, key: "An export assignment can only be used in a module." },
+        An_import_declaration_can_only_be_used_in_a_namespace_or_module: { code: 1232, category: DiagnosticCategory.Error, key: "An import declaration can only be used in a namespace or module." },
+        An_export_declaration_can_only_be_used_in_a_module: { code: 1233, category: DiagnosticCategory.Error, key: "An export declaration can only be used in a module." },
+        An_ambient_module_declaration_is_only_allowed_at_the_top_level_in_a_file: { code: 1234, category: DiagnosticCategory.Error, key: "An ambient module declaration is only allowed at the top level in a file." },
+        A_namespace_declaration_is_only_allowed_in_a_namespace_or_module: { code: 1235, category: DiagnosticCategory.Error, key: "A namespace declaration is only allowed in a namespace or module." },
         Duplicate_identifier_0: { code: 2300, category: DiagnosticCategory.Error, key: "Duplicate identifier '{0}'." },
         Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor: { code: 2301, category: DiagnosticCategory.Error, key: "Initializer of instance member variable '{0}' cannot reference identifier '{1}' declared in the constructor." },
         Static_members_cannot_reference_class_type_parameters: { code: 2302, category: DiagnosticCategory.Error, key: "Static members cannot reference class type parameters." },
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 08273011745..d78ea07f91a 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -731,6 +731,26 @@
         "category": "Error",
         "code": 1230
     },
+    "An export assignment can only be used in a module.": {
+        "category": "Error",
+        "code": 1231
+    },
+    "An import declaration can only be used in a namespace or module.": {
+        "category": "Error",
+        "code": 1232
+    },
+    "An export declaration can only be used in a module.": {
+        "category": "Error",
+        "code": 1233
+    },
+    "An ambient module declaration is only allowed at the top level in a file.": {
+        "category": "Error",
+        "code": 1234
+    },
+    "A namespace declaration is only allowed in a namespace or module.": {
+        "category": "Error",
+        "code": 1235
+    },
 
 
     "Duplicate identifier '{0}'.": {