diff --git a/radicale/acl/PAM.py b/radicale/acl/PAM.py
index d7d021b6..3399a3c7 100644
--- a/radicale/acl/PAM.py
+++ b/radicale/acl/PAM.py
@@ -26,6 +26,7 @@ Authentication based on the ``pam-python`` module.
 import grp
 import pam
 import pwd
+
 from radicale import acl, config, log