diff --git a/src/ast_handlers.hpp b/src/ast_handlers.hpp
index 2953dad..7099542 100644
--- a/src/ast_handlers.hpp
+++ b/src/ast_handlers.hpp
@@ -383,6 +383,8 @@
     }
 };
 
+struct commit_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)