diff --git a/staging/src/k8s.io/api/admissionregistration/v1alpha1/types.go b/staging/src/k8s.io/api/admissionregistration/v1alpha1/types.go
index 575456c8386..bd6b17e1588 100644
--- a/staging/src/k8s.io/api/admissionregistration/v1alpha1/types.go
+++ b/staging/src/k8s.io/api/admissionregistration/v1alpha1/types.go
@@ -226,7 +226,7 @@ type ValidatingAdmissionPolicySpec struct {
 	// +listType=map
 	// +listMapKey=name
 	// +optional
-	Variables []Variable `json:"variables" patchStrategy:"merge" patchMergeKey:"name" protobuf:"bytes,7,rep,name=variables"`
+	Variables []Variable `json:"variables,omitempty" patchStrategy:"merge" patchMergeKey:"name" protobuf:"bytes,7,rep,name=variables"`
 }
 
 type MatchCondition v1.MatchCondition
diff --git a/staging/src/k8s.io/api/admissionregistration/v1beta1/types.go b/staging/src/k8s.io/api/admissionregistration/v1beta1/types.go
index c199702fbd0..12c680dc972 100644
--- a/staging/src/k8s.io/api/admissionregistration/v1beta1/types.go
+++ b/staging/src/k8s.io/api/admissionregistration/v1beta1/types.go
@@ -242,7 +242,7 @@ type ValidatingAdmissionPolicySpec struct {
 	// +listType=map
 	// +listMapKey=name
 	// +optional
-	Variables []Variable `json:"variables" patchStrategy:"merge" patchMergeKey:"name" protobuf:"bytes,7,rep,name=variables"`
+	Variables []Variable `json:"variables,omitempty" patchStrategy:"merge" patchMergeKey:"name" protobuf:"bytes,7,rep,name=variables"`
 }
 
 // ParamKind is a tuple of Group Kind and Version.