diff --git a/CMakeLists.txt b/CMakeLists.txt
index e6ba3e8..4f2ff7a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(lilfbtf5 VERSION 0.1.37)
+project(lilfbtf5 VERSION 0.1.38)
 
 option(ENABLE_ADDRSAN "Enable the address sanitizer" OFF)
 option(ENABLE_UBSAN "Enable the ub sanitizer" OFF)
diff --git a/include/lilfbtf/tree.h b/include/lilfbtf/tree.h
index 3fcc798..484896e 100644
--- a/include/lilfbtf/tree.h
+++ b/include/lilfbtf/tree.h
@@ -66,8 +66,8 @@ namespace fb
             [[nodiscard]] inline function_id getFunction() const
             { return function; }
             
-            inline void call(blt::span<detail::node_t*> args)
-            { func(*this, args); };
+            inline void call(blt::span<detail::node_t*> args, blt::unsafe::buffer_any_t extra_args)
+            { func({*this, args, extra_args}); };
             
             ~func_t() = default;
     };
@@ -99,9 +99,9 @@ namespace fb
                         children[i] = nullptr;
                 }
                 
-                inline void evaluate()
+                inline void evaluate(blt::unsafe::buffer_any_t extra_args)
                 {
-                    type.call(blt::span<node_t*>{children, type.argc()});
+                    type.call(blt::span<node_t*>{children, type.argc()}, extra_args);
                 }
                 
                 inline blt::unsafe::any_t value()
@@ -173,7 +173,7 @@ namespace fb
             static tree_t make_tree(detail::tree_construction_info_t tree_info, blt::size_t min_depth, blt::size_t max_depth,
                                     std::optional<type_id> starting_type = {});
             
-            detail::tree_eval_t evaluate(const fitness_eval_func_t& fitnessEvalFunc);
+            detail::tree_eval_t evaluate(blt::unsafe::buffer_any_t extra_args, const fitness_eval_func_t& fitnessEvalFunc);
             
             blt::size_t depth();
             
diff --git a/libs/BLT b/libs/BLT
index 16641a2..1256ec2 160000
--- a/libs/BLT
+++ b/libs/BLT
@@ -1 +1 @@
-Subproject commit 16641a27cbe6fccb8f6a6518d903432311cbeb81
+Subproject commit 1256ec201cdb3a8d3d9bb4ebe9c25637a718465e
diff --git a/src/tree.cpp b/src/tree.cpp
index b683811..acc96b0 100644
--- a/src/tree.cpp
+++ b/src/tree.cpp
@@ -63,7 +63,7 @@ namespace fb
         return tree;
     }
     
-    detail::tree_eval_t tree_t::evaluate(const fitness_eval_func_t& fitnessEvalFunc)
+    detail::tree_eval_t tree_t::evaluate(blt::unsafe::buffer_any_t extra_args, const fitness_eval_func_t& fitnessEvalFunc)
     {
         using detail::node_t;
         std::stack<node_t*> nodes;
@@ -83,7 +83,7 @@ namespace fb
         
         while (!node_stack.empty())
         {
-            node_stack.top()->evaluate();
+            node_stack.top()->evaluate(extra_args);
             node_stack.pop();
         }
         
diff --git a/tests/src/main.cpp b/tests/src/main.cpp
index 563dd0e..dd2b14d 100644
--- a/tests/src/main.cpp
+++ b/tests/src/main.cpp
@@ -25,36 +25,6 @@ struct pixel
 
 const blt::size_t image_width = 128, image_height = 128;
 
-struct pixelator_t
-{
-    private:
-        blt::size_t width, height;
-        blt::size_t x = 0, y = 0;
-    public:
-        pixelator_t(blt::size_t width, blt::size_t height): width(width), height(height)
-        {}
-        
-        pixel next()
-        {
-            if (x > width)
-            {
-                x = 0;
-                y++;
-            }
-            return {x++, y};
-        }
-        
-        [[nodiscard]] inline blt::size_t curX() const
-        {
-            return x;
-        }
-        
-        [[nodiscard]] inline blt::size_t curY() const
-        {
-            return y;
-        }
-} pixelator{image_width, image_height};
-
 const fb::func_t_call_t add_f = [](const fb::detail::func_t_arguments& args) {
     args.self.setValue(args.arguments[0]->value().any_cast<blt::u8>() + args.arguments[1]->value().any_cast<blt::u8>());
 };
@@ -73,6 +43,12 @@ const fb::func_t_call_t div_f = [](const fb::detail::func_t_arguments& args) {
 };
 
 const fb::func_t_call_t empty_f = [](const fb::detail::func_t_arguments&) {};
+const fb::func_t_call_t coord_x_f = [](const fb::detail::func_t_arguments& args) {
+    args.self.setValue(args.extra_args.any_cast<pixel>().x);
+};
+const fb::func_t_call_t coord_y_f = [](const fb::detail::func_t_arguments& args) {
+    args.self.setValue(args.extra_args.any_cast<pixel>().y);
+};
 const fb::func_t_init_t value_init_f = [](fb::func_t& self) {
     self.setValue(fb::random_value());
 };