diff --git a/net/udp/udp_sendto_buffered.c b/net/udp/udp_sendto_buffered.c
index a2511924f14..c35f56cc3f8 100644
--- a/net/udp/udp_sendto_buffered.c
+++ b/net/udp/udp_sendto_buffered.c
@@ -435,7 +435,7 @@ static uint16_t sendto_eventhandler(FAR struct net_driver_s *dev,
        */
 
       sndlen = wrb->wb_iob->io_pktlen;
-      ninfo("wrb=%p sndlen=%u\n", wrb, sndlen);
+      ninfo("wrb=%p sndlen=%zu\n", wrb, sndlen);
 
 #ifdef NEED_IPDOMAIN_SUPPORT
       /* If both IPv4 and IPv6 support are enabled, then we will need to