diff --git a/rq/worker.py b/rq/worker.py
index 3ba297a..929f91d 100644
--- a/rq/worker.py
+++ b/rq/worker.py
@@ -166,11 +166,11 @@ class Worker(object):
 
     def queue_names(self):
         """Returns the queue names of this worker's queues."""
-        return map(lambda q: q.name, self.queues)
+        return list(map(lambda q: q.name, self.queues))
 
     def queue_keys(self):
         """Returns the Redis keys representing this worker's queues."""
-        return map(lambda q: q.key, self.queues)
+        return list(map(lambda q: q.key, self.queues))
 
     @property
     def name(self):