diff --git a/src/quic_tx.c b/src/quic_tx.c
index 37f46fe73..9a0898e5d 100644
--- a/src/quic_tx.c
+++ b/src/quic_tx.c
@@ -2012,7 +2012,20 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
 				goto comp_pkt_len;
 			}
 
-			if (!ack_frm_len && !qel->pktns->tx.pto_probe)
+			if (qel->pktns->tx.pto_probe) {
+				/* If a probing packets was asked and could not be built,
+				 * this is not because there was not enough room, but due to
+				 * its frames which were already acknowledeged.
+				 * (see qc_stream_frm_is_acked()) called by qc_build_frms().
+				 *
+				 * That said, the consequence must be the same: cancelling
+				 * the packet building as if there was not enough room.
+				 */
+				 qel->pktns->tx.pto_probe--;
+				 goto no_room;
+			}
+
+			if (!ack_frm_len)
 				goto no_room;
 		}
 	}