diff --git a/gunicorn/workers/async.py b/gunicorn/workers/async.py
index 3bf963c0..1e55789d 100644
--- a/gunicorn/workers/async.py
+++ b/gunicorn/workers/async.py
@@ -113,7 +113,7 @@ class AsyncWorker(base.Worker):
                     sock.close()
                 except socket.error:
                     pass
-                return
+                raise StopIteration()
             raise
         finally:
             try:
diff --git a/gunicorn/workers/sync.py b/gunicorn/workers/sync.py
index 347b6a28..b57f28b9 100644
--- a/gunicorn/workers/sync.py
+++ b/gunicorn/workers/sync.py
@@ -152,8 +152,7 @@ class SyncWorker(base.Worker):
                     client.close()
                 except socket.error:
                     pass
-
-                return
+                raise StopIteration()
             # Only send back traceback in HTTP in debug mode.
             self.handle_error(req, client, addr, e)
             return