diff --git a/api/v1alpha1/vrfrouteconfiguration_types.go b/api/v1alpha1/vrfrouteconfiguration_types.go
index 96796b7d..e2d0e111 100644
--- a/api/v1alpha1/vrfrouteconfiguration_types.go
+++ b/api/v1alpha1/vrfrouteconfiguration_types.go
@@ -71,6 +71,7 @@ type VRFRouteConfigurationSpec struct {
 	// Sequence of the generated route-map, maximum of 65534 because we sometimes have to set an explicit default-deny
 	Seq int `json:"seq"`
 
+	// +kubebuilder:validation:Optional
 	// +kubebuilder:default=9000
 	// The MTU of the VRF
 	MTU int `json:"mtu"`
diff --git a/config/crd/bases/network.schiff.telekom.de_vrfrouteconfigurations.yaml b/config/crd/bases/network.schiff.telekom.de_vrfrouteconfigurations.yaml
index 9cfb0749..7f73a23e 100644
--- a/config/crd/bases/network.schiff.telekom.de_vrfrouteconfigurations.yaml
+++ b/config/crd/bases/network.schiff.telekom.de_vrfrouteconfigurations.yaml
@@ -139,7 +139,6 @@ spec:
             required:
             - export
             - import
-            - mtu
             - seq
             type: object
           status:
diff --git a/pkg/nl/layer3.go b/pkg/nl/layer3.go
index 9b6fd5fe..1c8f4ed6 100644
--- a/pkg/nl/layer3.go
+++ b/pkg/nl/layer3.go
@@ -188,7 +188,7 @@ func (n *Manager) EnsureMTU(info VRFInformation) error {
 		return fmt.Errorf("error getting default2vrf interface of vrf %s: %w", info.Name, err)
 	}
 	if link.Attrs().MTU != info.linkMTU() {
-		if err := n.toolkit.LinkSetMTU(link, info.MTU); err != nil {
+		if err := n.toolkit.LinkSetMTU(link, info.linkMTU()); err != nil {
 			return fmt.Errorf("error setting MTU of default2vrw interface of vrf %s: %w", info.Name, err)
 		}
 	}