diff --git a/include/fmt/os.h b/include/fmt/os.h
index e5bd11aa..fd701555 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -13,8 +13,10 @@
 #include <cstdio>
 #include <system_error>  // std::system_error
 
-#if (defined __APPLE__ || defined(__FreeBSD__)) && __has_include(<xlocale.h>)
-#  include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
+#if defined __APPLE__ || defined(__FreeBSD__)
+#  if (__cplusplus < 201703L) || __has_include(<xlocale.h>)
+#    include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
+#  endif
 #endif
 
 #include "format.h"