diff --git a/intern/guardedalloc/intern/mmap_win.c b/intern/guardedalloc/intern/mmap_win.c
index 3c4607d0d2a..d8e53fc9bd1 100644
--- a/intern/guardedalloc/intern/mmap_win.c
+++ b/intern/guardedalloc/intern/mmap_win.c
@@ -42,6 +42,13 @@
 #define FILE_MAP_EXECUTE 0x0020
 #endif
 
+/* copied from BKE_utildefines.h ugh */
+#ifdef __GNUC__
+#  define UNUSED(x) UNUSED_ ## x __attribute__((__unused__))
+#else
+#  define UNUSED(x) x
+#endif
+
 /* --------------------------------------------------------------------- */
 /* local storage definitions                                                    */
 /* --------------------------------------------------------------------- */