diff --git a/update-firewall-source.py b/update-firewall-source.py
index a624440..97fcaa2 100644
--- a/update-firewall-source.py
+++ b/update-firewall-source.py
@@ -523,14 +523,14 @@ def write_new_fwd_direct_xml(
 
 def restart_systemd_firewalld() -> bool:
     sysbus = dbus.SystemBus()
-    systemd1 = sysbus.get_object('org.freedesktop.systemd1', '/org/freedesktop/systemd1')
-    manager = dbus.Interface(systemd1, 'org.freedesktop.systemd1.Manager')
+    systemd1 = sysbus.get_object("org.freedesktop.systemd1", "/org/freedesktop/systemd1")
+    manager = dbus.Interface(systemd1, "org.freedesktop.systemd1.Manager")
 
-    firewalld_unit = manager.LoadUnit('firewalld.service')
-    firewalld_proxy = sysbus.get_object('org.freedesktop.systemd1', str(firewalld_unit))
-    firewalld_active_state = firewalld_proxy.Get('org.freedesktop.systemd1.Unit',
-                                                 'ActiveState',
-                                                 dbus_interface='org.freedesktop.DBus.Properties')
+    firewalld_unit = manager.LoadUnit("firewalld.service")
+    firewalld_proxy = sysbus.get_object("org.freedesktop.systemd1", str(firewalld_unit))
+    firewalld_active_state = firewalld_proxy.Get("org.freedesktop.systemd1.Unit",
+                                                 "ActiveState",
+                                                 dbus_interface="org.freedesktop.DBus.Properties")
 
     if firewalld_active_state == "inactive":
         log.info(f"systemd firewalld.service unit is inactive, ignoring restart instruction, leaving as-is ...")
@@ -599,7 +599,7 @@ def has_xml_changed(
             return False
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     validate_default_section(config)
     if config_has_valid_section(config):
         validate_config_sections(config)