diff --git a/test/minigzip.c b/test/minigzip.c
index 7c9eb79..974a98d 100644
--- a/test/minigzip.c
+++ b/test/minigzip.c
@@ -15,6 +15,10 @@
 
 /* @(#) $Id$ */
 
+#ifndef _POSIX_C_SOURCE
+#  define _POSIX_C_SOURCE 200112L
+#endif
+
 #include "zlib.h"
 #include <stdio.h>