diff --git a/lib/adapters/http.js b/lib/adapters/http.js
index b31fbc8266..0985d7c87c 100755
--- a/lib/adapters/http.js
+++ b/lib/adapters/http.js
@@ -310,7 +310,7 @@ export default function httpAdapter(config) {
       return reject(customErr);
     }
 
-    headers.set('Accept-Encoding', 'gzip, deflate, gzip, br', false);
+    headers.set('Accept-Encoding', 'gzip, deflate, br', false);
 
     const options = {
       path: buildURL(parsed.path, config.params, config.paramsSerializer).replace(/^\?/, ''),