diff --git a/src/core/include/mp-units/bits/external/fixed_string.h b/src/core/include/mp-units/bits/external/fixed_string.h
index ad8d302f..402140c1 100644
--- a/src/core/include/mp-units/bits/external/fixed_string.h
+++ b/src/core/include/mp-units/bits/external/fixed_string.h
@@ -34,17 +34,6 @@
 #include <cstdlib>
 #include <ostream>
 #include <string_view>
-
-#if MP_UNITS_USE_FMTLIB
-MP_UNITS_DIAGNOSTIC_PUSH
-MP_UNITS_DIAGNOSTIC_IGNORE_UNREACHABLE
-MP_UNITS_DIAGNOSTIC_IGNORE_SHADOW
-#include <fmt/format.h>
-MP_UNITS_DIAGNOSTIC_POP
-#else
-#include <format>
-#endif
-
 #endif
 
 MP_UNITS_EXPORT
diff --git a/src/core/include/mp-units/bits/fmt.h b/src/core/include/mp-units/bits/fmt.h
index bd558724..8ffb7284 100644
--- a/src/core/include/mp-units/bits/fmt.h
+++ b/src/core/include/mp-units/bits/fmt.h
@@ -36,21 +36,6 @@
 #include <concepts>
 #include <limits>
 #include <string_view>
-
-#if MP_UNITS_USE_FMTLIB
-MP_UNITS_DIAGNOSTIC_PUSH
-MP_UNITS_DIAGNOSTIC_IGNORE_UNREACHABLE
-MP_UNITS_DIAGNOSTIC_IGNORE_SHADOW
-#include <fmt/format.h>
-MP_UNITS_DIAGNOSTIC_POP
-#else
-#include <format>
-#endif
-
-#ifndef MP_UNITS_IN_MODULE_INTERFACE
-#include <cstdint>
-#endif
-
 #endif
 
 // most of the below code is based on/copied from fmtlib
diff --git a/src/core/include/mp-units/compat_macros.h b/src/core/include/mp-units/compat_macros.h
index b379350f..0c3c9876 100644
--- a/src/core/include/mp-units/compat_macros.h
+++ b/src/core/include/mp-units/compat_macros.h
@@ -84,3 +84,18 @@
 #define MP_UNITS_THROW(arg) throw arg
 
 #endif
+
+
+#ifndef MP_UNITS_IN_MODULE_INTERFACE
+
+#if MP_UNITS_USE_FMTLIB
+MP_UNITS_DIAGNOSTIC_PUSH
+MP_UNITS_DIAGNOSTIC_IGNORE_UNREACHABLE
+MP_UNITS_DIAGNOSTIC_IGNORE_SHADOW
+#include <fmt/format.h>
+MP_UNITS_DIAGNOSTIC_POP
+#else
+#include <format>
+#endif
+
+#endif