diff --git a/gunicorn/workers/workertmp.py b/gunicorn/workers/workertmp.py
index 66defe94..604c759c 100644
--- a/gunicorn/workers/workertmp.py
+++ b/gunicorn/workers/workertmp.py
@@ -38,7 +38,7 @@ class WorkerTmp(object):
 
     def notify(self):
         new_time = time.monotonic()
-        os.utime(self._tmp.name, (new_time, new_time))
+        os.utime(self._tmp.fileno(), (new_time, new_time))
 
     def last_update(self):
         return os.fstat(self._tmp.fileno()).st_mtime