diff --git a/xdg_open_ng/default.nix b/xdg_open_ng/default.nix
index 0a0d371..aa3fed5 100644
--- a/xdg_open_ng/default.nix
+++ b/xdg_open_ng/default.nix
@@ -20,6 +20,7 @@ buildNimPackage rec {
     desktopName = "Syndicate URI dispatcher (xdg-open)";
     exec = "${name} %U";
     mimeTypes = [
+      "application/vnd.mozilla.xul+xml"
       "application/xhtml+xml"
       "text/html"
       "text/xml"