diff --git a/api/v1alpha1/runner_types.go b/api/v1alpha1/runner_types.go
index 99e1dd5e..c1f78071 100644
--- a/api/v1alpha1/runner_types.go
+++ b/api/v1alpha1/runner_types.go
@@ -130,6 +130,7 @@ type RunnerStatus struct {
 	// +optional
 	Message string `json:"message,omitempty"`
 	// +optional
+	// +nullable
 	LastRegistrationCheckTime *metav1.Time `json:"lastRegistrationCheckTime,omitempty"`
 }
 
diff --git a/charts/actions-runner-controller/Chart.yaml b/charts/actions-runner-controller/Chart.yaml
index 1c7b02db..2e698760 100644
--- a/charts/actions-runner-controller/Chart.yaml
+++ b/charts/actions-runner-controller/Chart.yaml
@@ -15,7 +15,7 @@ type: application
 # This is the chart version. This version number should be incremented each time you make changes
 # to the chart and its templates, including the app version.
 # Versions are expected to follow Semantic Versioning (https://semver.org/)
-version: 0.10.3
+version: 0.10.4
 
 home: https://github.com/summerwind/actions-runner-controller
 
diff --git a/charts/actions-runner-controller/crds/actions.summerwind.dev_runners.yaml b/charts/actions-runner-controller/crds/actions.summerwind.dev_runners.yaml
index 86d42c9c..fb53c769 100644
--- a/charts/actions-runner-controller/crds/actions.summerwind.dev_runners.yaml
+++ b/charts/actions-runner-controller/crds/actions.summerwind.dev_runners.yaml
@@ -1543,6 +1543,7 @@ spec:
           properties:
             lastRegistrationCheckTime:
               format: date-time
+              nullable: true
               type: string
             message:
               type: string
diff --git a/config/crd/bases/actions.summerwind.dev_runners.yaml b/config/crd/bases/actions.summerwind.dev_runners.yaml
index 86d42c9c..fb53c769 100644
--- a/config/crd/bases/actions.summerwind.dev_runners.yaml
+++ b/config/crd/bases/actions.summerwind.dev_runners.yaml
@@ -1543,6 +1543,7 @@ spec:
           properties:
             lastRegistrationCheckTime:
               format: date-time
+              nullable: true
               type: string
             message:
               type: string