diff --git a/CMakeLists.txt b/CMakeLists.txt
index 358f812..5f5877a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(lilfbtf5 VERSION 0.1.34)
+project(lilfbtf5 VERSION 0.1.35)
 
 option(ENABLE_ADDRSAN "Enable the address sanitizer" OFF)
 option(ENABLE_UBSAN "Enable the ub sanitizer" OFF)
diff --git a/include/lilfbtf/fwddecl.h b/include/lilfbtf/fwddecl.h
index 3aa7455..3aa17c8 100644
--- a/include/lilfbtf/fwddecl.h
+++ b/include/lilfbtf/fwddecl.h
@@ -44,6 +44,7 @@ namespace fb
     using arg_c_t = blt::size_t;
     using func_t_call_t = std::function<void(func_t&, blt::span<detail::node_t*>)>;
     using func_t_init_t = std::function<void(func_t&)>;
+    using fitness_eval_func_t = std::function<void(detail::node_t*)>;
     using function_name = const std::string&;
     using type_name = const std::string&;
 }