diff --git a/core/net/simple-udp.c b/core/net/simple-udp.c
index 38b7ef77e..97a39c89b 100644
--- a/core/net/simple-udp.c
+++ b/core/net/simple-udp.c
@@ -44,7 +44,7 @@
 #include "contiki-net.h"
 #include "net/simple-udp.h"
 
-#include <stdlib.h>
+#include <string.h>
 
 
 PROCESS(simple_udp_process, "Simple UDP process");