diff --git a/mockkubeapiserver/postresource.go b/mockkubeapiserver/postresource.go
index b54fecd7..6cfcdca1 100644
--- a/mockkubeapiserver/postresource.go
+++ b/mockkubeapiserver/postresource.go
@@ -105,7 +105,7 @@ func preCreateHook(ctx context.Context, obj *unstructured.Unstructured) error {
 			for k, vAny := range stringDataMap {
 				v, ok := vAny.(string)
 				if !ok {
-					return fmt.Errorf("unexpected type for v1.Secret stringData entry, got %T", vAny)
+					return fmt.Errorf("unexpected type for v1.Secret stringData entry %s: expected string, got %T", k, vAny)
 				}
 				dataMap[k] = base64.StdEncoding.EncodeToString([]byte(v))
 			}