diff --git a/lwip/src/arch/sys_arch.c b/lwip/src/arch/sys_arch.c
index ca3b15d4..2eef4727 100644
--- a/lwip/src/arch/sys_arch.c
+++ b/lwip/src/arch/sys_arch.c
@@ -141,6 +141,7 @@ u32_t sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout)
 		err = sem_trywait(&sem->sem);
 		if (err != -1)
 			return err;
+		udelay(1000);
 		timeout--;
 	}
 	return SYS_ARCH_TIMEOUT;
@@ -167,6 +168,7 @@ u32_t sys_arch_mbox_fetch(sys_mbox_t * mbox, void **msg, u32_t timeout)
 	{
 		if (!mailbox_ptr_tryfetch(&mbox->mailbox,msg))
 			return 0;
+		udelay(1000);
 		timeout--;
 	}