1 files changed, 1 insertions, 1 deletions
diff --git a/util.c b/util.c
index f39e17b8b7..3c08879ce5 100644
--- a/util.c
+++ b/util.c
@@ -14,7 +14,7 @@
 #endif
 
 #ifndef __STDC_WANT_LIB_EXT1__
-#define __STDC_WANT_LIB_EXT1__ 1
+#define __STDC_WANT_LIB_EXT1__ 1 /* for qsort_s() */
 #endif
 
 #include "ruby/internal/config.h"