diff --git a/exp/api/v1alpha3/conversion.go b/exp/api/v1alpha3/conversion.go
index 8f6903b81abc..b1eccab89345 100644
--- a/exp/api/v1alpha3/conversion.go
+++ b/exp/api/v1alpha3/conversion.go
@@ -76,6 +76,7 @@ func (src *MachinePool) ConvertTo(dstRaw conversion.Hub) error {
 	}
 	dst.Spec.Template.Spec.NodeDeletionTimeout = restored.Spec.Template.Spec.NodeDeletionTimeout
 	dst.Spec.Template.Spec.NodeVolumeDetachTimeout = restored.Spec.Template.Spec.NodeVolumeDetachTimeout
+	dst.Spec.Selector = restored.Spec.Selector
 	return nil
 }
 
diff --git a/exp/api/v1alpha4/conversion.go b/exp/api/v1alpha4/conversion.go
index fa9d49368d8d..d66548e85829 100644
--- a/exp/api/v1alpha4/conversion.go
+++ b/exp/api/v1alpha4/conversion.go
@@ -42,6 +42,7 @@ func (src *MachinePool) ConvertTo(dstRaw conversion.Hub) error {
 	}
 	dst.Spec.Template.Spec.NodeDeletionTimeout = restored.Spec.Template.Spec.NodeDeletionTimeout
 	dst.Spec.Template.Spec.NodeVolumeDetachTimeout = restored.Spec.Template.Spec.NodeVolumeDetachTimeout
+	dst.Spec.Selector = restored.Spec.Selector
 	return nil
 }
 
diff --git a/internal/webhooks/patch_validation.go b/internal/webhooks/patch_validation.go
index 81557bc06b57..d08016c3f9c9 100644
--- a/internal/webhooks/patch_validation.go
+++ b/internal/webhooks/patch_validation.go
@@ -207,6 +207,7 @@ func validateSelectors(selector clusterv1.PatchSelector, class *clusterv1.Cluste
 
 	if selector.MatchResources.MachineDeploymentClass != nil && len(selector.MatchResources.MachineDeploymentClass.Names) > 0 {
 		for i, name := range selector.MatchResources.MachineDeploymentClass.Names {
+			match := false
 			if strings.Contains(name, "*") {
 				// selector can at most have a single * rune
 				if strings.Count(name, "*") > 1 {
@@ -248,10 +249,18 @@ func validateSelectors(selector clusterv1.PatchSelector, class *clusterv1.Cluste
 				if matches {
 					if selectorMatchTemplate(selector, md.Template.Infrastructure.Ref) ||
 						selectorMatchTemplate(selector, md.Template.Bootstrap.Ref) {
+						match = true
 						break
 					}
 				}
 			}
+			if !match {
+				allErrs = append(allErrs, field.Invalid(
+					path.Child("matchResources", "machineDeploymentClass", "names").Index(i),
+					name,
+					"selector is enabled but matches neither the bootstrap ref nor the infrastructure ref of a MachineDeployment class",
+				))
+			}
 		}
 	}