diff --git a/packages/service-worker/worker/src/assets.ts b/packages/service-worker/worker/src/assets.ts
index 6b7f7373f5..b5dc2a9f04 100644
--- a/packages/service-worker/worker/src/assets.ts
+++ b/packages/service-worker/worker/src/assets.ts
@@ -193,9 +193,10 @@ export abstract class AssetGroup {
       cacheDirectives.forEach(v => v[0] = v[0].toLowerCase());
 
       // Find the max-age directive, if one exists.
-      const cacheAge = cacheDirectives.filter(v => v[0] === 'max-age').map(v => v[1])[0];
+      const maxAgeDirective = cacheDirectives.find(v => v[0] === 'max-age');
+      const cacheAge = maxAgeDirective ? maxAgeDirective[1] : undefined;
 
-      if (cacheAge.length === 0) {
+      if (!cacheAge) {
         // No usable TTL defined. Must assume that the response is stale.
         return true;
       }
diff --git a/packages/service-worker/worker/test/happy_spec.ts b/packages/service-worker/worker/test/happy_spec.ts
index 1b558ef799..4ca3969b4a 100644
--- a/packages/service-worker/worker/test/happy_spec.ts
+++ b/packages/service-worker/worker/test/happy_spec.ts
@@ -28,6 +28,7 @@ const dist =
         .addFile('/lazy/unchanged1.txt', 'this is unchanged (1)')
         .addFile('/lazy/unchanged2.txt', 'this is unchanged (2)')
         .addUnhashedFile('/unhashed/a.txt', 'this is unhashed', {'Cache-Control': 'max-age=10'})
+        .addUnhashedFile('/unhashed/b.txt', 'this is unhashed b', {'Cache-Control': 'no-cache'})
         .build();
 
 const distUpdate =
@@ -621,6 +622,13 @@ const manifestUpdateHash = sha1(JSON.stringify(manifestUpdate));
         server.assertNoOtherRequests();
       });
 
+      async_it(`doesn't error when 'Cache-Control' is 'no-cache'`, async() => {
+        expect(await makeRequest(scope, '/unhashed/b.txt')).toEqual('this is unhashed b');
+        server.assertSawRequestFor('/unhashed/b.txt');
+        expect(await makeRequest(scope, '/unhashed/b.txt')).toEqual('this is unhashed b');
+        server.assertNoOtherRequests();
+      });
+
       async_it('avoid opaque responses', async() => {
         expect(await makeRequest(scope, '/unhashed/a.txt', 'default', {
           credentials: 'include'