diff --git a/index.d.ts b/index.d.ts
index 45ad4374..909382cf 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -61,6 +61,7 @@ declare module 'mock-socket' {
   class Server extends EventTarget {
     constructor(url: string, options?: ServerOptions);
 
+    readonly url: string;
     readonly options?: ServerOptions;
 
     stop(callback?: () => void): void;
diff --git a/src/helpers/normalize-send.js b/src/helpers/normalize-send.js
index ebb209bb..4fa6f25b 100644
--- a/src/helpers/normalize-send.js
+++ b/src/helpers/normalize-send.js
@@ -1,5 +1,7 @@
 export default function normalizeSendData(data) {
-  if (Object.prototype.toString.call(data) !== '[object Blob]' && !(data instanceof ArrayBuffer)) {
+  if (data instanceof Buffer) {
+    data = data.buffer;
+  } else if (Object.prototype.toString.call(data) !== '[object Blob]' && !(data instanceof ArrayBuffer)) {
     data = String(data);
   }