diff --git a/src/core/include/units/bits/external/fixed_string.h b/src/core/include/units/bits/external/fixed_string.h
index 7b3ec35d..067a9c0c 100644
--- a/src/core/include/units/bits/external/fixed_string.h
+++ b/src/core/include/units/bits/external/fixed_string.h
@@ -22,6 +22,8 @@
 
 #pragma once
 
+#include <units/bits/external/hacks.h> // IWYU pragma: keep
+
 // IWYU pragma: begin_exports
 #include <cstdlib>
 #include <compare>