diff --git a/packages/language-service/BUILD.bazel b/packages/language-service/BUILD.bazel
index 3379d4e4f7..7239b0da4a 100644
--- a/packages/language-service/BUILD.bazel
+++ b/packages/language-service/BUILD.bazel
@@ -8,6 +8,7 @@ ts_library(
         "api.ts",
         "index.ts",
     ],
+    prodmode_module = "commonjs",
     deps = [
         "@npm//@types/node",
         "@npm//typescript",
diff --git a/packages/language-service/index.ts b/packages/language-service/index.ts
index 6b02ff5ca9..5d4e0219ce 100644
--- a/packages/language-service/index.ts
+++ b/packages/language-service/index.ts
@@ -9,8 +9,6 @@
 import * as ts from 'typescript/lib/tsserverlibrary';
 import {NgLanguageService, PluginConfig} from './api';
 
-export * from './api';
-
 interface PluginModule extends ts.server.PluginModule {
   create(createInfo: ts.server.PluginCreateInfo): NgLanguageService;
   onConfigurationChanged?(config: PluginConfig): void;
@@ -35,4 +33,9 @@ const factory: ts.server.PluginModuleFactory = (tsModule): PluginModule => {
   };
 };
 
-module.exports = factory;
+/**
+ * Tsserver expects `@angular/language-service` to provide a factory function
+ * as the default export of the package. See
+ * https://github.com/microsoft/TypeScript/blob/f4d0ea6539edb6d8f70b626132d6f9ac1ac4281a/src/server/project.ts#L1611
+ */
+export = factory;