diff --git a/models/site.rb b/models/site.rb
index 9f286ffe..68fd0181 100644
--- a/models/site.rb
+++ b/models/site.rb
@@ -57,7 +57,7 @@ class Site < Sequel::Model
   }
 
   VALID_EDITABLE_EXTENSIONS = %w{
-    html htm txt js css scss md manifest less webmanifest xml json opml rdf svg gpg pgp resolveHandle pls yaml yml toml osdx mjs cjs ts py rss glsl
+    html htm txt js css scss md manifest less webmanifest xml json opml rdf svg gpg pgp resolveHandle pls yaml yml toml osdx mjs cjs ts py rss glsl htx
   }
 
   MINIMUM_PASSWORD_LENGTH = 5