diff --git a/src/deep-linking.spec.ts b/src/deep-linking.spec.ts
index ebb32230..bd06764b 100644
--- a/src/deep-linking.spec.ts
+++ b/src/deep-linking.spec.ts
@@ -9,6 +9,11 @@ import * as helpers from './util/helpers';
 
 describe('Deep Linking task', () => {
   describe('deepLinkingWorkerImpl', () => {
+
+    beforeEach(() => {
+      deepLinking.reset();
+    });
+
     it('should not update app ngmodule when it has an existing deeplink config', () => {
       const appNgModulePath = join('some', 'fake', 'path', 'myApp', 'src', 'app', 'app.module.ts');
       const context = {
@@ -26,6 +31,7 @@ describe('Deep Linking task', () => {
       const promise = deepLinking.deepLinkingWorkerImpl(context, null);
 
       return promise.then(() => {
+        expect(deepLinking.cachedUnmodifiedAppNgModuleFileContent).toEqual(knownFileContent);
         expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).not.toHaveBeenCalled();
         expect(deeplinkUtils.updateAppNgModuleAndFactoryWithDeepLinkConfig).not.toHaveBeenCalled();
       });
@@ -73,6 +79,7 @@ describe('Deep Linking task', () => {
       const promise = deepLinking.deepLinkingWorkerImpl(context, changedFiles);
 
       return promise.then(() => {
+        expect(deepLinking.cachedDeepLinkString).toEqual(knownDeepLinkString);
         expect(helpers.getStringPropertyValue).toBeCalledWith(Constants.ENV_APP_NG_MODULE_PATH);
         expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledWith(appNgModulePath, context.fileCache, context.runAot);
         expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledWith(appNgModulePath, knownFileContent);
@@ -80,5 +87,110 @@ describe('Deep Linking task', () => {
         expect(deeplinkUtils.updateAppNgModuleAndFactoryWithDeepLinkConfig).toHaveBeenCalledWith(context, knownDeepLinkString, changedFiles, context.runAot);
       });
     });
+
+    it('should update deeplink config on subsequent updates when the deeplink string is different', () => {
+      const appNgModulePath = join('some', 'fake', 'path', 'myApp', 'src', 'app', 'app.module.ts');
+      const context = {
+        fileCache: new FileCache(),
+        runAot: true
+      };
+      const knownFileContent = 'someFileContent';
+      const knownDeepLinkString = 'someDeepLinkString';
+      const knownDeepLinkString2 = 'someDeepLinkString2';
+      const knownMockDeepLinkArray = [1];
+      const changedFiles: ChangedFile[] = null;
+      context.fileCache.set(appNgModulePath, { path: appNgModulePath, content: knownFileContent});
+
+      spyOn(helpers, helpers.getStringPropertyValue.name).and.returnValue(appNgModulePath);
+      spyOn(deeplinkUtils, deeplinkUtils.getDeepLinkData.name).and.returnValue(knownMockDeepLinkArray);
+      spyOn(deeplinkUtils, deeplinkUtils.hasExistingDeepLinkConfig.name).and.returnValue(false);
+
+      let hasConvertDeepLinkConfigToStringBeenCalled = false;
+      spyOn(deeplinkUtils, deeplinkUtils.convertDeepLinkConfigEntriesToString.name).and.callFake(() => {
+        if (!hasConvertDeepLinkConfigToStringBeenCalled) {
+          hasConvertDeepLinkConfigToStringBeenCalled = true;
+          return knownDeepLinkString;
+        }
+        return knownDeepLinkString2;
+      });
+
+      const spy = spyOn(deeplinkUtils, deeplinkUtils.updateAppNgModuleAndFactoryWithDeepLinkConfig.name);
+
+      const promise = deepLinking.deepLinkingWorkerImpl(context, changedFiles);
+
+      return promise.then(() => {
+        expect(deepLinking.cachedDeepLinkString).toEqual(knownDeepLinkString);
+        expect(helpers.getStringPropertyValue).toBeCalledWith(Constants.ENV_APP_NG_MODULE_PATH);
+        expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledWith(appNgModulePath, context.fileCache, context.runAot);
+        expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledWith(appNgModulePath, knownFileContent);
+        expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).toHaveBeenCalledWith(knownMockDeepLinkArray);
+        expect(spy.calls.first().args[0]).toEqual(context);
+        expect(spy.calls.first().args[1]).toEqual(knownDeepLinkString);
+        expect(spy.calls.first().args[2]).toEqual(changedFiles);
+        expect(spy.calls.first().args[3]).toEqual(context.runAot);
+
+        return deepLinking.deepLinkingWorkerImpl(context, changedFiles);
+      }).then((result) => {
+        expect(deepLinking.cachedDeepLinkString).toEqual(knownDeepLinkString2);
+        expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledTimes(2);
+        expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledWith(appNgModulePath, context.fileCache, context.runAot);
+        expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledTimes(2);
+        expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledWith(appNgModulePath, knownFileContent);
+        expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).toHaveBeenCalledWith(knownMockDeepLinkArray);
+        expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).toHaveBeenCalledTimes(2);
+        expect(spy).toHaveBeenCalledTimes(2);
+        expect(spy.calls.mostRecent().args[0]).toEqual(context);
+        expect(spy.calls.mostRecent().args[1]).toEqual(knownDeepLinkString2);
+        expect(spy.calls.mostRecent().args[2]).toEqual(changedFiles);
+        expect(spy.calls.mostRecent().args[3]).toEqual(context.runAot);
+      });
+    });
+
+    it('should not update deeplink config on subsequent updates when the deeplink string is the same', () => {
+      const appNgModulePath = join('some', 'fake', 'path', 'myApp', 'src', 'app', 'app.module.ts');
+      const context = {
+        fileCache: new FileCache(),
+        runAot: true
+      };
+      const knownFileContent = 'someFileContent';
+      const knownDeepLinkString = 'someDeepLinkString';
+      const knownMockDeepLinkArray = [1];
+      const changedFiles: ChangedFile[] = null;
+      context.fileCache.set(appNgModulePath, { path: appNgModulePath, content: knownFileContent});
+
+      spyOn(helpers, helpers.getStringPropertyValue.name).and.returnValue(appNgModulePath);
+      spyOn(deeplinkUtils, deeplinkUtils.getDeepLinkData.name).and.returnValue(knownMockDeepLinkArray);
+      spyOn(deeplinkUtils, deeplinkUtils.hasExistingDeepLinkConfig.name).and.returnValue(false);
+
+      spyOn(deeplinkUtils, deeplinkUtils.convertDeepLinkConfigEntriesToString.name).and.returnValue(knownDeepLinkString);
+
+      const spy = spyOn(deeplinkUtils, deeplinkUtils.updateAppNgModuleAndFactoryWithDeepLinkConfig.name);
+
+      const promise = deepLinking.deepLinkingWorkerImpl(context, changedFiles);
+
+      return promise.then(() => {
+        expect(deepLinking.cachedDeepLinkString).toEqual(knownDeepLinkString);
+        expect(helpers.getStringPropertyValue).toBeCalledWith(Constants.ENV_APP_NG_MODULE_PATH);
+        expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledWith(appNgModulePath, context.fileCache, context.runAot);
+        expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledWith(appNgModulePath, knownFileContent);
+        expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).toHaveBeenCalledWith(knownMockDeepLinkArray);
+        expect(spy.calls.first().args[0]).toEqual(context);
+        expect(spy.calls.first().args[1]).toEqual(knownDeepLinkString);
+        expect(spy.calls.first().args[2]).toEqual(changedFiles);
+        expect(spy.calls.first().args[3]).toEqual(context.runAot);
+
+        return deepLinking.deepLinkingWorkerImpl(context, changedFiles);
+      }).then((result) => {
+        expect(result).toEqual(knownMockDeepLinkArray);
+        expect(deepLinking.cachedDeepLinkString).toEqual(knownDeepLinkString);
+        expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledTimes(2);
+        expect(deeplinkUtils.getDeepLinkData).toHaveBeenCalledWith(appNgModulePath, context.fileCache, context.runAot);
+        expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledTimes(2);
+        expect(deeplinkUtils.hasExistingDeepLinkConfig).toHaveBeenCalledWith(appNgModulePath, knownFileContent);
+        expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).toHaveBeenCalledWith(knownMockDeepLinkArray);
+        expect(deeplinkUtils.convertDeepLinkConfigEntriesToString).toHaveBeenCalledTimes(2);
+        expect(spy).toHaveBeenCalledTimes(1);
+      });
+    });
   });
 });
diff --git a/src/deep-linking.ts b/src/deep-linking.ts
index f8ab95db..3831ecce 100644
--- a/src/deep-linking.ts
+++ b/src/deep-linking.ts
@@ -15,7 +15,8 @@ import { convertDeepLinkConfigEntriesToString, getDeepLinkData, hasExistingDeepL
  * as the cached version of the App's main NgModule content will basically always
  * have a generated deep likn config in it.
 */
-let cachedUnmodifiedAppNgModuleFileContent: string = null;
+export let cachedUnmodifiedAppNgModuleFileContent: string = null;
+export let cachedDeepLinkString: string = null;
 
 export function deepLinking(context: BuildContext) {
   const logger = new Logger(`deeplinks`);
@@ -42,12 +43,26 @@ export function deepLinkingWorkerImpl(context: BuildContext, changedFiles: Chang
     if (!cachedUnmodifiedAppNgModuleFileContent) {
       cachedUnmodifiedAppNgModuleFileContent = appNgModuleFile.content;
     }
-    const deepLinkConfigEntries = getDeepLinkData(appNgModulePath, context.fileCache, context.runAot);
+
+    // is there is an existing (legacy) deep link config, just move on and don't look for decorators
     const hasExisting = hasExistingDeepLinkConfig(appNgModulePath, cachedUnmodifiedAppNgModuleFileContent);
-    if (!hasExisting && deepLinkConfigEntries && deepLinkConfigEntries.length) {
-      // only update the app's main ngModule if there isn't an existing config
-      const deepLinkString = convertDeepLinkConfigEntriesToString(deepLinkConfigEntries);
-      updateAppNgModuleAndFactoryWithDeepLinkConfig(context, deepLinkString, changedFiles, context.runAot);
+    if (hasExisting) {
+      return [];
+    }
+
+    const deepLinkConfigEntries = getDeepLinkData(appNgModulePath, context.fileCache, context.runAot) || [];
+    if (deepLinkConfigEntries.length) {
+      const newDeepLinkString = convertDeepLinkConfigEntriesToString(deepLinkConfigEntries);
+      if (!cachedDeepLinkString) {
+        // this is the first time running this, so update the build either way
+        cachedDeepLinkString = newDeepLinkString;
+        updateAppNgModuleAndFactoryWithDeepLinkConfig(context, newDeepLinkString, changedFiles, context.runAot);
+      } else if (newDeepLinkString !== cachedDeepLinkString) {
+        // we have an existing deep link string, and we have a new one, and they're different
+        // so go ahead and update the config
+        cachedDeepLinkString = newDeepLinkString;
+        updateAppNgModuleAndFactoryWithDeepLinkConfig(context, newDeepLinkString, changedFiles, context.runAot);
+      }
     }
     return deepLinkConfigEntries;
   });
@@ -89,3 +104,9 @@ export function deepLinkingWorkerFullUpdate(context: BuildContext) {
       throw logger.fail(error);
     });
 }
+
+// this is purely for testing
+export function reset() {
+  cachedUnmodifiedAppNgModuleFileContent = null;
+  cachedDeepLinkString = null;
+}
\ No newline at end of file