diff --git a/tests/test_postfix.py b/tests/test_postfix.py
index 15afa1e2f1f24f25c81ae576a00f1e47e7ed7ff4..7cdebf28de82c856ea9bcdf9c3a9030812ca2cba 100755
--- a/tests/test_postfix.py
+++ b/tests/test_postfix.py
@@ -13,7 +13,7 @@ if not os.path.exists('/etc/postfix'):
     sys.exit(1)
 else:
     # check that postfix listens the port 25 correctly
-    status, out = subprocess.getstatusoutput('netstat -pant | grep master | grep 127.0.0.1:25', shell=True)
+    status, out = subprocess.getstatusoutput('netstat -pant | grep master | grep 127.0.0.1:25')
     if status != 0:
         print('The port 25 is not listened by any process.')
         sys.exit(1)