diff --git a/modules/languages/siren-conf.el b/modules/languages/siren-conf.el
index 9abb06b..3a86973 100644
--- a/modules/languages/siren-conf.el
+++ b/modules/languages/siren-conf.el
@@ -16,6 +16,8 @@
   "/\\.env\\.[^/]+\\'"
   "\\.cfg\\'"
   "\\.conf\\'"
+  "\\tool-versions\\'"
+  "\\.tool-versions\\'"
 
   :hook (conf-mode . siren-conf-mode-setup)