diff --git a/src/des/main.c b/src/des/main.c
index b0b7c4ef99..79fa2b43bb 100644
--- a/src/des/main.c
+++ b/src/des/main.c
@@ -17,6 +17,16 @@ RCSID("$Header$");
 
 #include <mit-cpyright.h>
 #include <stdio.h>
+#include <stdlib.h>
+
+#ifdef HAVE_STRING_H
+#include <string.h>
+#else
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
+#endif
+#endif
+
 #include "des_internal.h"
 
 extern void gen PROTOTYPE((FILE * stream));
diff --git a/src/des/make_ip.c b/src/des/make_ip.c
index e84d8ac486..5c9afd6de5 100644
--- a/src/des/make_ip.c
+++ b/src/des/make_ip.c
@@ -15,6 +15,7 @@ RCSID("$Header$");
 
 #include <mit-cpyright.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include "des_internal.h"
 
 #define WANT_IP_TABLE