diff --git a/gunicorn/arbiter.py b/gunicorn/arbiter.py
index 882d63f0..df2616f3 100644
--- a/gunicorn/arbiter.py
+++ b/gunicorn/arbiter.py
@@ -482,7 +482,7 @@ class Arbiter(object):
             (pid, _) = workers.pop(0)
             self.kill_worker(pid, signal.SIGTERM)
 
-        self.log.debug("{0} workers".format(len(workers),
+        self.log.debug("{0} workers".format(len(workers)),
                         extra={ "metric": "gunicorn.workers",
                                 "value": len(workers),
                                 "mtype": "gauge"})