diff --git a/interpreter/valid/valid.ml b/interpreter/valid/valid.ml
index 285b7b54..85edc7d7 100644
--- a/interpreter/valid/valid.ml
+++ b/interpreter/valid/valid.ml
@@ -196,7 +196,7 @@ let check_memory_type (c : context) (mt : memory_type) at =
 
 let check_tag_type (c : context) (et : tag_type) at =
   match et with
-  | TagT ft -> check_heap_type c ft at
+  | TagT ht -> check_heap_type c ht at
 
 let check_global_type (c : context) (gt : global_type) at =
   let GlobalT (_mut, t) = gt in