diff --git a/lib/tftp.c b/lib/tftp.c
index 8ee947dfdb..449a2b3d2a 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -420,7 +420,7 @@ static CURLcode tftp_rx(tftp_state_data_t *state, tftp_event_t event)
     }
 
     /* Check if completed (That is, a less than full packet is received) */
-    if(state->rbytes < sizeof(state->spacket)){
+    if(state->rbytes < (ssize_t)sizeof(state->spacket)){
       state->state = TFTP_STATE_FIN;
     }
     else {