diff --git a/internal/ackhandler/sent_packet_handler.go b/internal/ackhandler/sent_packet_handler.go
index f6de118a..51e28fc0 100644
--- a/internal/ackhandler/sent_packet_handler.go
+++ b/internal/ackhandler/sent_packet_handler.go
@@ -246,6 +246,7 @@ func (h *sentPacketHandler) ReceivedAck(ackFrame *wire.AckFrame, withPacketNumbe
 
 	h.ptoCount = 0
 	h.cryptoCount = 0
+	h.numProbesToSend = 0
 
 	h.updateLossDetectionAlarm()
 	return nil
diff --git a/internal/ackhandler/sent_packet_handler_test.go b/internal/ackhandler/sent_packet_handler_test.go
index 10d6d18e..cde872df 100644
--- a/internal/ackhandler/sent_packet_handler_test.go
+++ b/internal/ackhandler/sent_packet_handler_test.go
@@ -680,6 +680,16 @@ var _ = Describe("SentPacketHandler", func() {
 			Expect(handler.retransmissionQueue).To(BeEmpty()) // 1 and 2 were already sent as probe packets
 		})
 
+		It("resets the send mode when it receives an acknowledgement after queueing probe packets", func() {
+			handler.SentPacket(retransmittablePacket(&Packet{PacketNumber: 1, SendTime: time.Now().Add(-time.Hour)}))
+			handler.rttStats.UpdateRTT(time.Second, 0, time.Now())
+			handler.OnAlarm()
+			Expect(handler.SendMode()).To(Equal(SendPTO))
+			ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 1}}}
+			Expect(handler.ReceivedAck(ack, 1, protocol.Encryption1RTT, time.Now())).To(Succeed())
+			Expect(handler.SendMode()).To(Equal(SendAny))
+		})
+
 		It("gets packets sent before the probe packet for retransmission", func() {
 			handler.SentPacket(retransmittablePacket(&Packet{PacketNumber: 1, SendTime: time.Now().Add(-time.Hour)}))
 			handler.SentPacket(retransmittablePacket(&Packet{PacketNumber: 2, SendTime: time.Now().Add(-time.Hour)}))