diff --git a/src/core/include/mp-units/bits/fmt.h b/src/core/include/mp-units/bits/fmt.h
index 626a3bc8..4d1848e6 100644
--- a/src/core/include/mp-units/bits/fmt.h
+++ b/src/core/include/mp-units/bits/fmt.h
@@ -30,7 +30,7 @@
 #pragma once
 
 #include <gsl/gsl-lite.hpp>
-#include <mp-units/bits/external/hacks.h>
+#include <mp-units/compat_macros.h>
 #include <concepts>
 #include <limits>
 #include <string_view>
diff --git a/src/core/include/mp-units/customization_points.h b/src/core/include/mp-units/customization_points.h
index e085514c..2741679e 100644
--- a/src/core/include/mp-units/customization_points.h
+++ b/src/core/include/mp-units/customization_points.h
@@ -22,7 +22,6 @@
 
 #pragma once
 
-#include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/external/type_traits.h>
 #include <limits>
 #include <type_traits>
diff --git a/src/core/include/mp-units/math.h b/src/core/include/mp-units/math.h
index ac9ecae9..cf5ab987 100644
--- a/src/core/include/mp-units/math.h
+++ b/src/core/include/mp-units/math.h
@@ -22,7 +22,6 @@
 
 #pragma once
 
-#include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/value_cast.h>
 #include <mp-units/customization_points.h>
 #include <mp-units/quantity.h>
diff --git a/src/core/include/mp-units/reference.h b/src/core/include/mp-units/reference.h
index 589d9bb6..eb0f34c5 100644
--- a/src/core/include/mp-units/reference.h
+++ b/src/core/include/mp-units/reference.h
@@ -22,7 +22,6 @@
 
 #pragma once
 
-#include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/get_associated_quantity.h>
 #include <mp-units/bits/quantity_concepts.h>
 #include <mp-units/bits/reference_concepts.h>
diff --git a/src/systems/include/mp-units/systems/angular/math.h b/src/systems/include/mp-units/systems/angular/math.h
index 70c0fc41..4d863a0b 100644
--- a/src/systems/include/mp-units/systems/angular/math.h
+++ b/src/systems/include/mp-units/systems/angular/math.h
@@ -23,7 +23,6 @@
 #pragma once
 
 #ifndef MP_UNITS_IN_MODULE_INTERFACE
-#include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/value_cast.h>
 #include <mp-units/customization_points.h>
 #include <mp-units/quantity.h>
diff --git a/src/systems/include/mp-units/systems/si/math.h b/src/systems/include/mp-units/systems/si/math.h
index 77722828..053d9b36 100644
--- a/src/systems/include/mp-units/systems/si/math.h
+++ b/src/systems/include/mp-units/systems/si/math.h
@@ -23,7 +23,6 @@
 #pragma once
 
 #ifndef MP_UNITS_IN_MODULE_INTERFACE
-#include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/value_cast.h>
 #include <mp-units/customization_points.h>
 #include <mp-units/quantity.h>