diff --git a/mockkubeapiserver/postresource.go b/mockkubeapiserver/postresource.go
index 668fcb42..b54fecd7 100644
--- a/mockkubeapiserver/postresource.go
+++ b/mockkubeapiserver/postresource.go
@@ -100,7 +100,7 @@ func preCreateHook(ctx context.Context, obj *unstructured.Unstructured) error {
 			}
 			dataMap, ok := dataAny.(map[string]any)
 			if !ok {
-				return fmt.Errorf("unexpected type for v1.Secret data, got %T", dataAny)
+				return fmt.Errorf("unexpected type for v1.Secret data: expected map[string]any, got %T", dataAny)
 			}
 			for k, vAny := range stringDataMap {
 				v, ok := vAny.(string)