diff --git a/src/ast_handlers.hpp b/src/ast_handlers.hpp
index 686ae30..580ea86 100644
--- a/src/ast_handlers.hpp
+++ b/src/ast_handlers.hpp
@@ -53,6 +53,8 @@
     }
 };
 
+struct key_identifier_class;
+
 struct module_identifier_class;
 
 struct listPrefix_class {