diff --git a/build/gulpfile.editor.js b/build/gulpfile.editor.js
index 3d8a85fd7f9..3b3fe4942d8 100644
--- a/build/gulpfile.editor.js
+++ b/build/gulpfile.editor.js
@@ -34,6 +34,7 @@ const editorEntryPoints = [
 	{
 		name: 'vs/base/common/worker/simpleWorker',
 		include: ['vs/editor/common/services/editorSimpleWorker'],
+		exclude: ['vs/nls'],
 		prepend: ['vs/loader.js'],
 		append: ['vs/base/worker/workerMain'],
 		dest: 'vs/base/worker/workerMain.js'
diff --git a/build/lib/bundle.js b/build/lib/bundle.js
index 8c1967d4c68..4cf08aef429 100644
--- a/build/lib/bundle.js
+++ b/build/lib/bundle.js
@@ -298,9 +298,18 @@ function emitEntryPoint(modulesMap, deps, entryPoint, includedModules, prepend,
         if (module.shim) {
             mainResult.sources.push(emitShimmedModule(c, deps[c], module.shim, module.path, contents));
         }
-        else {
+        else if (module.defineLocation) {
             mainResult.sources.push(emitNamedModule(c, module.defineLocation, module.path, contents));
         }
+        else {
+            const moduleCopy = {
+                id: module.id,
+                path: module.path,
+                defineLocation: module.defineLocation,
+                dependencies: module.dependencies
+            };
+            throw new Error(`Cannot bundle module '${module.id}' for entry point '${entryPoint}' because it has no shim and it lacks a defineLocation: ${JSON.stringify(moduleCopy)}`);
+        }
     });
     Object.keys(usedPlugins).forEach((pluginName) => {
         const plugin = usedPlugins[pluginName];
diff --git a/build/lib/bundle.ts b/build/lib/bundle.ts
index a1130d4bbbd..4c8a3e14589 100644
--- a/build/lib/bundle.ts
+++ b/build/lib/bundle.ts
@@ -15,7 +15,7 @@ interface IPosition {
 interface IBuildModuleInfo {
 	id: string;
 	path: string;
-	defineLocation: IPosition;
+	defineLocation: IPosition | null;
 	dependencies: string[];
 	shim: string;
 	exports: any;
@@ -444,8 +444,16 @@ function emitEntryPoint(
 
 		if (module.shim) {
 			mainResult.sources.push(emitShimmedModule(c, deps[c], module.shim, module.path, contents));
-		} else {
+		} else if (module.defineLocation) {
 			mainResult.sources.push(emitNamedModule(c, module.defineLocation, module.path, contents));
+		} else {
+			const moduleCopy = {
+				id: module.id,
+				path: module.path,
+				defineLocation: module.defineLocation,
+				dependencies: module.dependencies
+			};
+			throw new Error(`Cannot bundle module '${module.id}' for entry point '${entryPoint}' because it has no shim and it lacks a defineLocation: ${JSON.stringify(moduleCopy)}`);
 		}
 	});
 
diff --git a/src/buildfile.js b/src/buildfile.js
index 6b49aa30083..f0f49f65459 100644
--- a/src/buildfile.js
+++ b/src/buildfile.js
@@ -32,12 +32,14 @@ exports.base = [
 	{
 		name: 'vs/editor/common/services/editorSimpleWorker',
 		include: ['vs/base/common/worker/simpleWorker'],
+		exclude: ['vs/nls'],
 		prepend: ['vs/loader.js', 'vs/nls.js'],
 		append: ['vs/base/worker/workerMain'],
 		dest: 'vs/base/worker/workerMain.js'
 	},
 	{
 		name: 'vs/base/common/worker/simpleWorker',
+		exclude: ['vs/nls'],
 	}
 ];