diff --git a/apps/v1/types.go b/apps/v1/types.go
index 74c0ad66d8..28474be7f4 100644
--- a/apps/v1/types.go
+++ b/apps/v1/types.go
@@ -282,6 +282,7 @@ type StatefulSetStatus struct {
 
 	// Total number of available pods (ready for at least minReadySeconds) targeted by this statefulset.
 	// This is a beta field and enabled/disabled by StatefulSetMinReadySeconds feature gate.
+	// +optional
 	AvailableReplicas int32 `json:"availableReplicas" protobuf:"varint,11,opt,name=availableReplicas"`
 }
 
diff --git a/apps/v1beta1/types.go b/apps/v1beta1/types.go
index 08a36f5182..cdc81c956a 100644
--- a/apps/v1beta1/types.go
+++ b/apps/v1beta1/types.go
@@ -321,6 +321,7 @@ type StatefulSetStatus struct {
 
 	// Total number of available pods (ready for at least minReadySeconds) targeted by this StatefulSet.
 	// This is a beta field and enabled/disabled by StatefulSetMinReadySeconds feature gate.
+	// +optional
 	AvailableReplicas int32 `json:"availableReplicas" protobuf:"varint,11,opt,name=availableReplicas"`
 }
 
diff --git a/apps/v1beta2/types.go b/apps/v1beta2/types.go
index a93ef4f954..6c2448869e 100644
--- a/apps/v1beta2/types.go
+++ b/apps/v1beta2/types.go
@@ -330,6 +330,7 @@ type StatefulSetStatus struct {
 
 	// Total number of available pods (ready for at least minReadySeconds) targeted by this StatefulSet.
 	// This is a beta field and enabled/disabled by StatefulSetMinReadySeconds feature gate.
+	// +optional
 	AvailableReplicas int32 `json:"availableReplicas" protobuf:"varint,11,opt,name=availableReplicas"`
 }