diff --git a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.c b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.c
index 329e0f8de..7d39c9520 100644
--- a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.c
+++ b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.c
@@ -98,7 +98,7 @@ sys_mbox_t sys_mbox_new(int size) {
   sys_mbox_t mbox;
 
   mbox = chHeapAlloc(sizeof(Mailbox) + sizeof(msg_t) * size);
-  chMBInit(mbox, (void *)(mbox + 1), size);
+  chMBInit(mbox, (void *)(((uint8_t *)mbox) + sizeof(Mailbox)), size);
   return mbox;
 }
 
diff --git a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.h b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.h
index 2b503154c..a054ae761 100644
--- a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.h
+++ b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/arch/sys_arch.h
@@ -57,11 +57,11 @@
 #define __SYS_ARCH_H__
 
 typedef Semaphore *     sys_sem_t;
-typedef void *          sys_mbox_t;
+typedef Mailbox *       sys_mbox_t;
 typedef Thread *        sys_thread_t;
 typedef int             sys_prot_t;
 
-#define SYS_MBOX_NULL   (void *)0
+#define SYS_MBOX_NULL   (Mailbox *)0
 #define SYS_THREAD_NULL (Thread *)0
 #define SYS_SEM_NULL    (Semaphore *)0
 
diff --git a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/lwipthread.c b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/lwipthread.c
index 7b9d483c4..16957811e 100644
--- a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/lwipthread.c
+++ b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwip/lwipthread.c
@@ -274,13 +274,9 @@ msg_t lwip_thread(void *p) {
           /* full packet send to tcpip_thread to process */
           if (thisif.input(p, &thisif) != ERR_OK) {
             LWIP_DEBUGF(NETIF_DEBUG, ("ethernetif_input: IP input error\n"));
-            pbuf_free(p);
-            p = NULL;
           }
-          break;
         default:
           pbuf_free(p);
-          break;
         }
       }
     }
diff --git a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwipopts.h b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwipopts.h
index 318ee6579..ddb3aac11 100644
--- a/demos/ARM7-AT91SAM7X-LWIP-GCC/lwipopts.h
+++ b/demos/ARM7-AT91SAM7X-LWIP-GCC/lwipopts.h
@@ -1019,7 +1019,7 @@
  * sys_mbox_new() when tcpip_init is called.
  */
 #ifndef TCPIP_MBOX_SIZE
-#define TCPIP_MBOX_SIZE                 0
+#define TCPIP_MBOX_SIZE                 4
 #endif
 
 /**
@@ -1035,7 +1035,7 @@
  * sys_thread_new() when the thread is created.
  */
 #ifndef SLIPIF_THREAD_STACKSIZE
-#define SLIPIF_THREAD_STACKSIZE         0
+#define SLIPIF_THREAD_STACKSIZE         512
 #endif
 
 /**
@@ -1044,7 +1044,7 @@
  * sys_thread_new() when the thread is created.
  */
 #ifndef SLIPIF_THREAD_PRIO
-#define SLIPIF_THREAD_PRIO              1
+#define SLIPIF_THREAD_PRIO              (LOWPRIO + 1)
 #endif
 
 /**
@@ -1060,7 +1060,7 @@
  * sys_thread_new() when the thread is created.
  */
 #ifndef PPP_THREAD_STACKSIZE
-#define PPP_THREAD_STACKSIZE            0
+#define PPP_THREAD_STACKSIZE            512
 #endif
 
 /**
@@ -1069,7 +1069,7 @@
  * sys_thread_new() when the thread is created.
  */
 #ifndef PPP_THREAD_PRIO
-#define PPP_THREAD_PRIO                 1
+#define PPP_THREAD_PRIO                 (LOWPRIO + 1)
 #endif
 
 /**
@@ -1085,7 +1085,7 @@
  * sys_thread_new() when the thread is created.
  */
 #ifndef DEFAULT_THREAD_STACKSIZE
-#define DEFAULT_THREAD_STACKSIZE        0
+#define DEFAULT_THREAD_STACKSIZE        512
 #endif
 
 /**
@@ -1094,7 +1094,7 @@
  * sys_thread_new() when the thread is created.
  */
 #ifndef DEFAULT_THREAD_PRIO
-#define DEFAULT_THREAD_PRIO             1
+#define DEFAULT_THREAD_PRIO             (LOWPRIO + 1)
 #endif
 
 /**
@@ -1103,7 +1103,7 @@
  * to sys_mbox_new() when the recvmbox is created.
  */
 #ifndef DEFAULT_RAW_RECVMBOX_SIZE
-#define DEFAULT_RAW_RECVMBOX_SIZE       0
+#define DEFAULT_RAW_RECVMBOX_SIZE       4
 #endif
 
 /**
@@ -1112,7 +1112,7 @@
  * to sys_mbox_new() when the recvmbox is created.
  */
 #ifndef DEFAULT_UDP_RECVMBOX_SIZE
-#define DEFAULT_UDP_RECVMBOX_SIZE       0
+#define DEFAULT_UDP_RECVMBOX_SIZE       4
 #endif
 
 /**
@@ -1121,7 +1121,7 @@
  * to sys_mbox_new() when the recvmbox is created.
  */
 #ifndef DEFAULT_TCP_RECVMBOX_SIZE
-#define DEFAULT_TCP_RECVMBOX_SIZE       0
+#define DEFAULT_TCP_RECVMBOX_SIZE       40
 #endif
 
 /**
@@ -1130,7 +1130,7 @@
  * sys_mbox_new() when the acceptmbox is created.
  */
 #ifndef DEFAULT_ACCEPTMBOX_SIZE
-#define DEFAULT_ACCEPTMBOX_SIZE         0
+#define DEFAULT_ACCEPTMBOX_SIZE         4
 #endif
 
 /*