diff --git a/CMakeLists.txt b/CMakeLists.txt
index f9e722b..c1fce15 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(lilfbtf5 VERSION 0.1.25)
+project(lilfbtf5 VERSION 0.1.26)
 
 option(ENABLE_ADDRSAN "Enable the address sanitizer" OFF)
 option(ENABLE_UBSAN "Enable the ub sanitizer" OFF)
diff --git a/include/lilfbtf/type.h b/include/lilfbtf/type.h
index 9669682..9005563 100644
--- a/include/lilfbtf/type.h
+++ b/include/lilfbtf/type.h
@@ -126,7 +126,7 @@ namespace fb
             associative_array<function_id, std::vector<type_id>, true> function_inputs;
             associative_array<function_id, arg_c_t> function_argc;
             
-            associative_array<function_id, std::reference_wrapper<const func_t_init_t>> function_initializer;
+            blt::hashmap_t<function_id, std::reference_wrapper<const func_t_init_t>> function_initializer;
             associative_array<type_id, std::vector<function_id>, true> terminals;
             associative_array<type_id, std::vector<function_id>, true> non_terminals;
             std::vector<std::pair<type_id, function_id>> all_non_terminals;
@@ -164,10 +164,14 @@ namespace fb
             [[nodiscard]] inline const func_t_call_t& get_function(function_name name) const
             { return get_function(get_function_id(name)); }
             
-            [[nodiscard]] inline const func_t_init_t& get_function_initializer(function_id id) const
-            { return function_initializer[id]; }
+            [[nodiscard]] inline std::optional<std::reference_wrapper<const func_t_init_t>> get_function_initializer(function_id id) const
+            {
+                if (!function_initializer.contains(id))
+                    return {};
+                return function_initializer.at(id);
+            }
             
-            [[nodiscard]] inline const func_t_init_t& get_function_initializer(function_name name) const
+            [[nodiscard]] inline std::optional<std::reference_wrapper<const func_t_init_t>> get_function_initializer(function_name name) const
             { return get_function_initializer(get_function_id(name)); }
             
             // output type -> list of functions that output that type and take arguments themselves
diff --git a/src/tree.cpp b/src/tree.cpp
index 2ffc3ec..3380107 100644
--- a/src/tree.cpp
+++ b/src/tree.cpp
@@ -37,6 +37,8 @@ namespace fb
             auto& non_terminals = types.get_all_non_terminals();
             auto selection = non_terminals[engine.random_long(0, non_terminals.size() - 1)];
             func_t func(types.get_function_argc(selection.second), types.get_function(selection.second), selection.first, selection.second);
+            if (const auto& func_init = types.get_function_initializer(selection.second))
+                func_init.value()(func);
             tree.root = tree.alloc.template emplace<node_t>(func, tree.alloc);
         }
         std::stack<std::pair<node_t*, blt::size_t>> stack;
@@ -64,6 +66,8 @@ namespace fb
                 {
                     function_id selection = non_terminals[engine.random_long(0, non_terminals.size() - 1)];
                     func_t func(types.get_function_argc(selection), types.get_function(selection), type_category, selection);
+                    if (const auto& func_init = types.get_function_initializer(selection))
+                        func_init.value()(func);
                     node->children[i] = tree.alloc.template emplace<node_t>(func, tree.alloc);
                     has_one_non_terminal = true;
                     continue;
@@ -73,6 +77,8 @@ namespace fb
                 {
                     function_id selection = terminals[engine.random_long(0, terminals.size() - 1)];
                     func_t func(types.get_function_argc(selection), types.get_function(selection), type_category, selection);
+                    if (const auto& func_init = types.get_function_initializer(selection))
+                        func_init.value()(func);
                     node->children[i] = tree.alloc.template emplace<node_t>(func, tree.alloc);
                     continue;
                 }
@@ -82,6 +88,8 @@ namespace fb
                     // use full() method
                     function_id selection = non_terminals[engine.random_long(0, non_terminals.size() - 1)];
                     func_t func(types.get_function_argc(selection), types.get_function(selection), type_category, selection);
+                    if (const auto& func_init = types.get_function_initializer(selection))
+                        func_init.value()(func);
                     node->children[i] = tree.alloc.template emplace<node_t>(func, tree.alloc);
                 } else
                 {
@@ -91,12 +99,16 @@ namespace fb
                         // use non-terminals
                         function_id selection = non_terminals[engine.random_long(0, non_terminals.size() - 1)];
                         func_t func(types.get_function_argc(selection), types.get_function(selection), type_category, selection);
+                        if (const auto& func_init = types.get_function_initializer(selection))
+                            func_init.value()(func);
                         node->children[i] = tree.alloc.template emplace<node_t>(func, tree.alloc);
                     } else
                     {
                         // use terminals
                         function_id selection = terminals[engine.random_long(0, terminals.size() - 1)];
                         func_t func(types.get_function_argc(selection), types.get_function(selection), type_category, selection);
+                        if (const auto& func_init = types.get_function_initializer(selection))
+                            func_init.value()(func);
                         node->children[i] = tree.alloc.template emplace<node_t>(func, tree.alloc);
                     }
                 }