diff --git a/library/fastd_key b/library/fastd_key
index 6113d8b..99e4982 100644
--- a/library/fastd_key
+++ b/library/fastd_key
@@ -21,7 +21,7 @@ if __name__ == '__main__':
   # file does not exist or is empty?
   if not os.path.isfile(path) or os.stat(path).st_size == 0:
     # create file with restrictive permissions
-    with os.fdopen(os.open(path, os.O_WRONLY | os.O_CREAT, 0600), 'w') as handle:
+    with os.fdopen(os.open(path, os.O_WRONLY | os.O_CREAT, 0o600), 'w') as handle:
       # generate fastd secret
       secret = subprocess.check_output(["fastd", "--machine-readable", "--generate-key"]).strip()
       handle.write('secret "%s";\n' % secret)