diff --git a/lib/des/mdtest.c b/lib/des/mdtest.c
index b3c56f082..14ca168b9 100644
--- a/lib/des/mdtest.c
+++ b/lib/des/mdtest.c
@@ -37,7 +37,7 @@ RCSID("$Id$");
 #endif
 
 #include <stdio.h>
-#ifdef HAVE_STDLIB
+#ifdef HAVE_STDLIB_H
 #include <stdlib.h>
 #endif
 #include <string.h>