diff --git a/packages/@ngtools/webpack/src/compiler_host.ts b/packages/@ngtools/webpack/src/compiler_host.ts
index d7af11ada7c6..df8cd1d221b9 100644
--- a/packages/@ngtools/webpack/src/compiler_host.ts
+++ b/packages/@ngtools/webpack/src/compiler_host.ts
@@ -187,8 +187,10 @@ export class WebpackCompilerHost implements ts.CompilerHost {
   }
 
   invalidate(fileName: string): void {
-    this._files[fileName] = null;
-    this._changedFiles[fileName] = true;
+    if (fileName in this._files) {
+      this._files[fileName] = null;
+      this._changedFiles[fileName] = true;
+    }
   }
 
   fileExists(fileName: string): boolean {
diff --git a/packages/angular-cli/lib/config/schema.d.ts b/packages/angular-cli/lib/config/schema.d.ts
new file mode 100644
index 000000000000..c34275a2522a
--- /dev/null
+++ b/packages/angular-cli/lib/config/schema.d.ts
@@ -0,0 +1,133 @@
+export interface CliConfig {
+    /**
+     * The global configuration of the project.
+     */
+    project?: {
+        version?: string;
+        name?: string;
+    };
+    /**
+     * Properties of the different applications in this project.
+     */
+    apps?: {
+        root?: string;
+        outDir?: string;
+        assets?: (string | string[]);
+        deployUrl?: string;
+        index?: string;
+        main?: string;
+        polyfills?: string;
+        test?: string;
+        tsconfig?: string;
+        prefix?: string;
+        mobile?: boolean;
+        /**
+         * Global styles to be included in the build.
+         */
+        styles?: (string | {
+            input?: string;
+            [name: string]: any;
+        })[];
+        /**
+         * Options to pass to style preprocessors
+         */
+        stylePreprocessorOptions?: {
+            /**
+             * Paths to include. Paths will be resolved to project root.
+             */
+            includePaths?: string[];
+        };
+        /**
+         * Global scripts to be included in the build.
+         */
+        scripts?: (string | {
+            input: string;
+            [name: string]: any;
+        })[];
+        /**
+         * Name and corresponding file for environment config.
+         */
+        environments?: {
+            [name: string]: any;
+        };
+    }[];
+    /**
+     * Configuration reserved for installed third party addons.
+     */
+    addons?: {
+        [name: string]: any;
+    }[];
+    /**
+     * Configuration reserved for installed third party packages.
+     */
+    packages?: {
+        [name: string]: any;
+    }[];
+    e2e?: {
+        protractor?: {
+            config?: string;
+        };
+    };
+    /**
+     * Properties to be passed to TSLint.
+     */
+    lint?: {
+        files: string;
+        project: string;
+        tslintConfig?: string;
+    }[];
+    test?: {
+        karma?: {
+            config?: string;
+        };
+    };
+    defaults?: {
+        styleExt?: string;
+        prefixInterfaces?: boolean;
+        poll?: number;
+        viewEncapsulation?: string;
+        changeDetection?: string;
+        inline?: {
+            style?: boolean;
+            template?: boolean;
+        };
+        spec?: {
+            class?: boolean;
+            component?: boolean;
+            directive?: boolean;
+            module?: boolean;
+            pipe?: boolean;
+            service?: boolean;
+        };
+        /**
+         * Properties to be passed to the serve command
+         */
+        serve?: {
+            /**
+             * The port the application will be served on
+             */
+            port?: number;
+            /**
+             * The host the application will be served on
+             */
+            host?: string;
+        };
+    };
+    /**
+     * Allow people to disable console warnings.
+     */
+    warnings?: {
+        /**
+         * Show a warning when the node version is incompatible.
+         */
+        nodeDeprecation?: boolean;
+        /**
+         * Show a warning when the user installed angular-cli.
+         */
+        packageDeprecation?: boolean;
+        /**
+         * Show a warning when the global version is newer than the local one.
+         */
+        versionMismatch?: boolean;
+    };
+}
diff --git a/tests/e2e/tests/build/rebuild-css-change.ts b/tests/e2e/tests/build/rebuild-css-change.ts
new file mode 100644
index 000000000000..8e8a9ce1fdfd
--- /dev/null
+++ b/tests/e2e/tests/build/rebuild-css-change.ts
@@ -0,0 +1,29 @@
+import {
+  killAllProcesses,
+  exec,
+  waitForAnyProcessOutputToMatch,
+  silentExecAndWaitForOutputToMatch
+} from '../../utils/process';
+import {appendToFile} from '../../utils/fs';
+
+const webpackGoodRegEx = /webpack: bundle is now VALID|webpack: Compiled successfully./;
+const webpackBadRegEx = /webpack: bundle is now INVALID|webpack: Compiling.../;
+
+export default function() {
+  if (process.platform.startsWith('win')) {
+    return Promise.resolve();
+  }
+
+  return silentExecAndWaitForOutputToMatch('ng', ['serve'], webpackGoodRegEx)
+    // Should trigger a rebuild.
+    .then(() => exec('touch', 'src/main.ts'))
+    .then(() => waitForAnyProcessOutputToMatch(webpackBadRegEx, 1000))
+    .then(() => waitForAnyProcessOutputToMatch(webpackGoodRegEx, 5000))
+    .then(() => appendToFile('src/app/app.component.css', ':host { color: blue; }'))
+    .then(() => waitForAnyProcessOutputToMatch(webpackBadRegEx, 1000))
+    .then(() => waitForAnyProcessOutputToMatch(webpackGoodRegEx, 5000))
+    .then(() => killAllProcesses(), (err: any) => {
+      killAllProcesses();
+      throw err;
+    });
+}