diff --git a/lib/des/mdtest.c b/lib/des/mdtest.c
index 286ee4d06..f58e4be84 100644
--- a/lib/des/mdtest.c
+++ b/lib/des/mdtest.c
@@ -37,6 +37,9 @@ RCSID("$Id$");
 #endif
 
 #include <stdio.h>
+#ifdef HAVE_STDLIB
+#include <stdlib.h>
+#endif
 #include <string.h>
 #include <md4.h>
 #include <md5.h>