diff --git a/library/src/main/java/com/evernote/android/job/Job.java b/library/src/main/java/com/evernote/android/job/Job.java
index 1a1d92bc..cbbd5341 100644
--- a/library/src/main/java/com/evernote/android/job/Job.java
+++ b/library/src/main/java/com/evernote/android/job/Job.java
@@ -113,7 +113,7 @@ public enum Result {
      */
     @NonNull
     @WorkerThread
-    protected abstract Result onRunJob(Params params);
+    protected abstract Result onRunJob(@NonNull Params params);
 
     /*package*/ final Result runJob() {
         try {