--- a/mobile/android/base/reading/ReadingListSyncAdapter.java
+++ b/mobile/android/base/reading/ReadingListSyncAdapter.java
@@ -255,16 +255,21 @@ public class ReadingListSyncAdapter exte
         BaseResource.removeHttpResponseObserver(observer);
         long backoffInSeconds = observer.largestBackoffObservedInSeconds.get();
         if (backoffInSeconds > 0) {
           Logger.warn(LOG_TAG, "Observed " + backoffInSeconds + "-second backoff request.");
           storageBackoffHandler.extendEarliestNextRequest(System.currentTimeMillis() + 1000 * backoffInSeconds);
         }
       }
 
+      if (result == null) {
+        // The poll timed out. Let's call this an error.
+        result = Result.Error;
+      }
+
       switch (result) {
       case Success:
         requestPeriodicSync(account, ReadingListSyncAdapter.AFTER_SUCCESS_SYNC_DELAY_SECONDS);
         break;
       case Error:
         requestPeriodicSync(account, ReadingListSyncAdapter.AFTER_ERROR_SYNC_DELAY_SECONDS);
         break;
       case Postponed: