diff --git a/kustomize/deployment.yaml b/kustomize/deployment.yaml
index 4e49c5c..908dc9e 100644
--- a/kustomize/deployment.yaml
+++ b/kustomize/deployment.yaml
@@ -28,3 +28,4 @@ spec:
                 secretKeyRef:
                   name: toy-session-secret
                   key: toy-session-secret
+                  optional: true