diff --git a/src/core/tcp.c b/src/core/tcp.c
index 458c6e07..663a5d9b 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -293,6 +293,7 @@ tcp_bind(struct tcp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
 static err_t
 tcp_accept_null(void *arg, struct tcp_pcb *pcb, err_t err)
 {
+  if (arg || pcb || err);
   return ERR_ABRT;
 }
 #endif /* LWIP_CALLBACK_API */
diff --git a/src/netif/etharp.c b/src/netif/etharp.c
index 0a4a652f..bb051f41 100644
--- a/src/netif/etharp.c
+++ b/src/netif/etharp.c
@@ -645,6 +645,8 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
   struct pbuf *p;
   err_t result;
   u8_t i;
+  /* prevent warning if ARP_QUEUEING == 0 */
+  if (q);
 
   srcaddr = (struct eth_addr *)netif->hwaddr;
   /* bail out if this IP address is pending */