diff --git a/rq/job.py b/rq/job.py
index ea25269..b3800a5 100644
--- a/rq/job.py
+++ b/rq/job.py
@@ -606,12 +606,9 @@ class Job(object):
             self.delete(pipeline=pipeline, remove_from_queue=remove_from_queue)
         elif not ttl:
             return
-        else:
+        elif ttl > 0:
             connection = pipeline if pipeline is not None else self.connection
-            if ttl > 0:
-                connection.expire(self.key, ttl)
-            else:
-                connection.persist(self.key)
+            connection.expire(self.key, ttl)
 
     def register_dependency(self, pipeline=None):
         """Jobs may have dependencies. Jobs are enqueued only if the job they
diff --git a/tests/test_queue.py b/tests/test_queue.py
index 3eea3fb..7129452 100644
--- a/tests/test_queue.py
+++ b/tests/test_queue.py
@@ -654,9 +654,10 @@ class TestFailedQueue(RQTestCase):
     def test_job_in_failed_queue_persists(self):
         """Make sure failed job key does not expire"""
         q = Queue('foo')
-        job = q.enqueue(div_by_zero, args=(1, 2, 3), ttl=5)
+        job = q.enqueue(div_by_zero, args=(1,), ttl=5)
         self.assertEqual(self.testconn.ttl(job.key), 5) 
-        
+
+        self.assertRaises(ZeroDivisionError, job.perform)
         job.set_status(JobStatus.FAILED)
         failed_queue = get_failed_queue()
         failed_queue.quarantine(job, Exception('Some fake error'))