diff --git a/src/core/include/units/magnitude.h b/src/core/include/units/magnitude.h
index 3860f326..0dbbb4bf 100644
--- a/src/core/include/units/magnitude.h
+++ b/src/core/include/units/magnitude.h
@@ -22,6 +22,7 @@
 
 #pragma once
 
+#include <units/bits/external/hacks.h>
 #include <units/ratio.h>
 #include <cstdint>
 #include <numbers>