diff --git a/cluster/addons/runtimeclass/runtimeclass_crd.yaml b/cluster/addons/runtimeclass/runtimeclass_crd.yaml
index 1c135098603..cbb09740e2f 100644
--- a/cluster/addons/runtimeclass/runtimeclass_crd.yaml
+++ b/cluster/addons/runtimeclass/runtimeclass_crd.yaml
@@ -23,4 +23,4 @@ spec:
           properties:
             runtimeHandler:
               type: string
-              pattern: '^[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*$'
+              pattern: '^([a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*)?$'