diff --git a/src/core/include/mp-units/format.h b/src/core/include/mp-units/format.h
index 58655021..f7b40f2a 100644
--- a/src/core/include/mp-units/format.h
+++ b/src/core/include/mp-units/format.h
@@ -24,6 +24,7 @@
 
 #include <mp-units/bits/external/algorithm.h>
 #include <mp-units/bits/fmt.h>
+#include <mp-units/compat_macros.h>
 #include <mp-units/customization_points.h>
 #include <mp-units/quantity.h>
 #include <mp-units/unit.h>