diff --git a/qemu/tests/balloon_stress.py b/qemu/tests/balloon_stress.py
index bb85137266fcd01194dc7a52c0087069d2ace659..e34cfa5330a896c4d492f1aafac2e891a1cb9538 100644
--- a/qemu/tests/balloon_stress.py
+++ b/qemu/tests/balloon_stress.py
@@ -58,8 +58,8 @@ def run(test, params, env):
     # need to wait for wmplayer loading remote video
     time.sleep(float(params.get("loading_timeout", 60)))
     check_playing_cmd = params["check_playing_cmd"]
-    fuc = lambda: session.cmd_status(check_playing_cmd) == 0
-    running = utils.wait_for(fuc, first=5.0, timeout=600)
+    running = utils.wait_for(lambda: session.cmd_status(check_playing_cmd) == 0,
+                             first=5.0, timeout=600)
     if not running:
         raise error.TestError("Video do not playing")