diff --git a/onionshare/onionshare.py b/onionshare/onionshare.py
index 6662e980..28744d2c 100644
--- a/onionshare/onionshare.py
+++ b/onionshare/onionshare.py
@@ -225,7 +225,7 @@ def tails_root():
         # close hole in firewall on shutdown
         import signal
 
-        def handler(signum = None, frame = None):
+        def handler(signum=None, frame=None):
             subprocess.call(['/sbin/iptables', '-D', 'OUTPUT', '-o', 'lo', '-p', 'tcp', '--dport', str(port), '-j', 'ACCEPT'])
             sys.exit()
         for sig in [signal.SIGTERM, signal.SIGINT, signal.SIGHUP, signal.SIGQUIT]: