diff --git a/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook.go b/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook.go
index ea2a5da88824..aa238eaddd09 100644
--- a/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook.go
+++ b/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook.go
@@ -78,6 +78,7 @@ func (in *KubeadmControlPlane) ValidateUpdate(old runtime.Object) error {
 		{spec, "infrastructureTemplate", "name"},
 		{spec, "replicas"},
 		{spec, "version"},
+		{spec, "upgradeAfter"},
 	}
 
 	allErrs := in.validateCommon()
diff --git a/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook_test.go b/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook_test.go
index dc3471928416..c01bab40594c 100644
--- a/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook_test.go
+++ b/controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook_test.go
@@ -178,6 +178,8 @@ func TestKubeadmControlPlaneValidateUpdate(t *testing.T) {
 	validUpdate.Spec.Version = "v1.16.6"
 	validUpdate.Spec.InfrastructureTemplate.Name = "orange"
 	validUpdate.Spec.Replicas = pointer.Int32Ptr(5)
+	now := metav1.NewTime(time.Now())
+	validUpdate.Spec.UpgradeAfter = &now
 
 	scaleToZero := before.DeepCopy()
 	scaleToZero.Spec.Replicas = pointer.Int32Ptr(0)