diff --git a/src/thai/AllTha.gf b/src/thai/AllTha.gf
index 985e6aba3..311a68bc4 100644
--- a/src/thai/AllTha.gf
+++ b/src/thai/AllTha.gf
@@ -1,3 +1,3 @@
 --# -path=.:../abstract:../common:../api
 
-concrete AllTha of AllThaAbs = LangTha ;
+concrete AllTha of AllThaAbs = LangTha, ExtendTha ;