diff --git a/libnmstate/ifaces/ifaces.py b/libnmstate/ifaces/ifaces.py
index a400712..1c2ffd5 100644
--- a/libnmstate/ifaces/ifaces.py
+++ b/libnmstate/ifaces/ifaces.py
@@ -217,7 +217,8 @@ class Ifaces:
                     self._ifaces[iface_name].mark_as_changed()
             if cur_iface:
                 for slave_name in iface.config_changed_slaves(cur_iface):
-                    self._ifaces[slave_name].mark_as_changed()
+                    if slave_name in self._ifaces:
+                        self._ifaces[slave_name].mark_as_changed()
 
     def _match_child_iface_state_with_parent(self):
         """