diff --git a/lib/des/rnd_keys.c b/lib/des/rnd_keys.c
index 689c7b9bb..f3c1fe503 100644
--- a/lib/des/rnd_keys.c
+++ b/lib/des/rnd_keys.c
@@ -12,6 +12,7 @@ RCSID("$Id$");
 #include <unistd.h>
 #include <signal.h>
 #include <fcntl.h>
+#include <string.h>
 
 /*
  * Generate "random" data by checksumming a file.