diff --git a/src/include/lwip/sys.h b/src/include/lwip/sys.h
index 9f62c754..dc935133 100644
--- a/src/include/lwip/sys.h
+++ b/src/include/lwip/sys.h
@@ -51,16 +51,22 @@ typedef u8_t sys_mbox_t;
 #define sys_sem_wait(s)
 #define sys_arch_sem_wait(s,t)
 #define sys_sem_free(s)
+#define sys_sem_valid(s) 0
+#define sys_sem_set_invalid(s)
 #define sys_mutex_new(mu) ERR_OK
 #define sys_mutex_lock(mu)
 #define sys_mutex_unlock(mu)
 #define sys_mutex_free(mu)
+#define sys_mutex_valid(mu) 0
+#define sys_mutex_set_invalid(mu)
 #define sys_mbox_new(m, s) ERR_OK
 #define sys_mbox_fetch(m,d)
 #define sys_mbox_tryfetch(m,d)
 #define sys_mbox_post(m,d)
 #define sys_mbox_trypost(m,d)
 #define sys_mbox_free(m)
+#define sys_mbox_valid(m)
+#define sys_mbox_set_invalid(m)
 
 #define sys_thread_new(n,t,a,s,p)