diff --git a/lib/des/rnd_keys.c b/lib/des/rnd_keys.c
index dc8a20017..4312d24d8 100644
--- a/lib/des/rnd_keys.c
+++ b/lib/des/rnd_keys.c
@@ -42,6 +42,7 @@ RCSID("$Id$");
 #endif
 #include <des.h>
 
+#include <stdlib.h>
 #include <string.h>
 
 #ifdef TIME_WITH_SYS_TIME