diff --git a/function_traits.h b/function_traits.h
index d64a42e..62bca0c 100644
--- a/function_traits.h
+++ b/function_traits.h
@@ -2,6 +2,8 @@ static_assert( __cplusplus > 2020'00 );
 
 #pragma once
 
+#include <Alepha/Alepha.h>
+
 #include <tuple>
 #include <type_traits>
 #include <functional>
diff --git a/meta.h b/meta.h
index 0162c6d..8e8ab38 100644
--- a/meta.h
+++ b/meta.h
@@ -2,6 +2,8 @@ static_assert( __cplusplus > 2020'00 );
 
 #pragma once
 
+#include <Alepha/Alepha.h>
+
 #include <type_traits>
 #include <tuple>
 #include <vector>
diff --git a/type_lisp.h b/type_lisp.h
index 94d0134..d64a8ef 100644
--- a/type_lisp.h
+++ b/type_lisp.h
@@ -2,6 +2,8 @@ static_assert( __cplusplus > 2020'00 );
 
 #pragma once
 
+#include <Alepha/Alepha.h>
+
 #include <type_traits>
 
 namespace Alepha::Hydrogen  ::detail::  type_lisp