diff --git a/src/mock/d2-mock/patch/withCredentials.js b/src/mock/d2-mock/patch/withCredentials.js
index 085a9145..160af951 100644
--- a/src/mock/d2-mock/patch/withCredentials.js
+++ b/src/mock/d2-mock/patch/withCredentials.js
@@ -4,7 +4,10 @@ export default function (Mock) {
   Mock.XHR.prototype.send = function () {
     if (this.custom.xhr) {
       this.custom.xhr.withCredentials = this.withCredentials || false
-      this.custom.xhr.responseType = this.responseType
+      // https://github.com/d2-projects/d2-admin/issues/254
+      if (!this.custom.async) {
+        this.custom.xhr.responseType = this.responseType
+      }
     }
     this.__send.apply(this, arguments)
   }