diff --git a/lib/tftp.c b/lib/tftp.c
index 09350ecc4..976e5044c 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -204,7 +204,7 @@ static CURLcode tftp_set_timeouts(tftp_state_data_t *state)
 {
   time_t maxtime, timeout;
   long timeout_ms;
-  const bool start = (state->state == TFTP_STATE_START);
+  bool start = (bool)(state->state == TFTP_STATE_START);
 
   time(&state->start_time);