diff --git a/src/h5ai/options.js b/src/h5ai/options.js
index 163b3298..02221cb7 100644
--- a/src/h5ai/options.js
+++ b/src/h5ai/options.js
@@ -57,7 +57,7 @@ h5aiOptions = {
      * possible values. Adjust it to your needs. If lang is not found in
      * h5aiLangs it defaults to "en".
      */
-    "lang": null,
+    "lang": "en",
 
     /*
      * Try to use browser language, falls back to previous specified lang.