diff --git a/src/ast_handlers.hpp b/src/ast_handlers.hpp
index 352824e..5cbb993 100644
--- a/src/ast_handlers.hpp
+++ b/src/ast_handlers.hpp
@@ -311,6 +311,8 @@
 
 struct cancel_class;
 
+struct quit_class;
+
 struct command_class {
     template <typename Iterator, typename Exception, typename Context>
     x3::error_handler_result on_error(Iterator&, Iterator const&, Exception const& x, Context const& context)