diff --git a/addons/web_chat/static/src/web_chat.html b/addons/web_chat/static/src/web_chat.html
index 5f11f01ee7b..a1070ab475a 100644
--- a/addons/web_chat/static/src/web_chat.html
+++ b/addons/web_chat/static/src/web_chat.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <html>
 <head>
 <script type="text/javascript" src="/web_chat/static/lib/AjaxIM/js/jquery-1.3.2.js"></script>