diff --git a/src/services/services.ts b/src/services/services.ts
index bd77b2d5c0d..f83202df864 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1810,13 +1810,21 @@ module ts {
         }
 
         /// Completion
-        function getValidCompletionEntryDisplayName(displayName: string, target: ScriptTarget): string {
+        function getValidCompletionEntryDisplayName(symbol: Symbol, target: ScriptTarget): string {
+            var displayName = symbol.getName();
             if (displayName && displayName.length > 0) {
                 var firstCharCode = displayName.charCodeAt(0);
+                // First check of the displayName is not external module; if it is an external module, it is not valid entry
+                if ((symbol.flags & SymbolFlags.Namespace) && (firstCharCode === CharacterCodes.singleQuote || firstCharCode === CharacterCodes.doubleQuote)) {
+                    // If the symbol is external module, don't show it in the completion list
+                    // (i.e declare module "http" { var x; } | // <= request completion here, "http" should not be there)
+                    return undefined;
+                }
+
                 if (displayName && displayName.length >= 2 && firstCharCode === displayName.charCodeAt(displayName.length - 1) &&
                     (firstCharCode === CharacterCodes.singleQuote || firstCharCode === CharacterCodes.doubleQuote)) {
                     // If the user entered name for the symbol was quoted, removing the quotes is not enough, as the name could be an
-                    // invalid identifer name. We need to check if whatever was inside the quotes is actually a valid identifier name.
+                    // invalid identifier name. We need to check if whatever was inside the quotes is actually a valid identifier name.
                     displayName = displayName.substring(1, displayName.length - 1);
                 }
                 
@@ -1825,6 +1833,7 @@ module ts {
                     isValid = isIdentifierPart(displayName.charCodeAt(i), target);
                 }
 
+
                 if (isValid) {
                     return displayName;
                 }
@@ -1837,7 +1846,7 @@ module ts {
             // Try to get a valid display name for this symbol, if we could not find one, then ignore it. 
             // We would like to only show things that can be added after a dot, so for instance numeric properties can
             // not be accessed with a dot (a.1 <- invalid)
-            var displayName = getValidCompletionEntryDisplayName(symbol.getName(), program.getCompilerOptions().target);
+            var displayName = getValidCompletionEntryDisplayName(symbol, program.getCompilerOptions().target);
             if (!displayName) {
                 return undefined;
             }
diff --git a/tests/cases/fourslash/completionListWithAmbientDeclaration.ts b/tests/cases/fourslash/completionListWithAmbientDeclaration.ts
new file mode 100644
index 00000000000..afb5d96fbb7
--- /dev/null
+++ b/tests/cases/fourslash/completionListWithAmbientDeclaration.ts
@@ -0,0 +1,15 @@
+/// <reference path="fourslash.ts"/>
+
+//// declare module "http" {
+////    var x;
+////    /*1*/
+//// }
+//// declare module 'https' {
+//// }
+//// /*2*/
+
+goTo.marker("1");
+verify.not.completionListContains("http");
+goTo.marker("2");
+verify.not.completionListContains("http");
+verify.not.completionListContains("https");