diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index 9a40a0dd5e..cf6baf47a1 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -8139,8 +8139,10 @@ _commit_mtu (NMDevice *self, const NMIP4Config *config)
 	if (ifindex <= 0)
 		return;
 
-	if (nm_device_sys_iface_state_is_external_or_assume (self)) {
-		/* for assumed connections we don't tamper with the MTU. */
+	if (   !nm_device_get_applied_connection (self)
+	    || nm_device_sys_iface_state_is_external_or_assume (self)) {
+		/* we don't tamper with the MTU of disconnected and
+		 * external/assumed devices. */
 		return;
 	}