diff --git a/lib/mockResponse.js b/lib/mockResponse.js
index 26746bd..cf6e72a 100644
--- a/lib/mockResponse.js
+++ b/lib/mockResponse.js
@@ -167,7 +167,7 @@ function createResponse(options = {}) {
                     _data = data;
                 }
             } else {
-                _data += data || '';
+                _data += data ?? '';
             }
         };