diff --git a/lib/tftp.c b/lib/tftp.c
index c09aadc03ee8b41e57d67af433b1d790ef54f1d9..c02337f99d3ee33708cd3315ef623d0d6ebd6500 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -759,8 +759,7 @@ static CURLcode tftp_tx(tftp_state_data_t *state, tftp_event_t event)
       state->state = TFTP_STATE_FIN;
       return CURLE_OK;
     }
-    res = Curl_fillreadbuffer(state->conn, (size_t)state->blksize,
-                              &state->sbytes);
+    res = Curl_fillreadbuffer(state->conn, state->blksize, &state->sbytes);
     if(res)
       return res;
     sbytes = sendto(state->sockfd, (void *)state->spacket.data,