diff --git a/src/sys/net/api/tcpip.c b/src/sys/net/api/tcpip.c
index fdf7926..51dc327 100644
--- a/src/sys/net/api/tcpip.c
+++ b/src/sys/net/api/tcpip.c
@@ -124,12 +124,12 @@
   msg->msg.apimsg = apimsg;
   sys_mbox_post(mbox, msg);
 }
-/*-----------------------------------------------------------------------------------*/
+
 void tcpip_init(void (*initfunc)(void *), void *arg) {
   tcpip_init_done = initfunc;
   tcpip_init_done_arg = arg;
+  if (mbox != 0x0)
+    kpanic("Already Allocated!");
   mbox = sys_mbox_new();
   sys_thread_new((void *) tcpip_thread, NULL);
 }
-/*-----------------------------------------------------------------------------------*/
-