--- gtksourceview/gtksourceutils.c	2026-03-17 04:22:41.000000000 +0800
+++ gtksourceview/gtksourceutils.c	2026-05-05 02:38:29.000000000 +0800
@@ -30,7 +30,11 @@
 
 #include "config.h"
 
-#define _GNU_SOURCE
+#ifdef __APPLE__
+# define _DARWIN_C_SOURCE
+#else
+# define _GNU_SOURCE
+#endif
 
 #if defined(HAVE_POSIX_MEMALIGN) && !defined(_XOPEN_SOURCE)
 # define _XOPEN_SOURCE 600