diff --git a/ultramodern/utils.hpp b/ultramodern/utils.hpp
index d921b68..e61e45f 100644
--- a/ultramodern/utils.hpp
+++ b/ultramodern/utils.hpp
@@ -1,3 +1,6 @@
+#ifndef __utils_HPP__
+#define __utils_HPP__
+
 #include <variant>
 
 template<class... Ts> 
@@ -9,4 +12,6 @@ struct overloaded : Ts...
 template<class T, class... Ts>
 auto match(const T& event, Ts&&... args){
     return std::visit(overloaded{std::forward<Ts>(args)...}, event);
-}
\ No newline at end of file
+}
+
+#endif