diff --git a/ackhandler/sent_packet_handler.go b/ackhandler/sent_packet_handler.go
index c587ad6fd..ffb089fa5 100644
--- a/ackhandler/sent_packet_handler.go
+++ b/ackhandler/sent_packet_handler.go
@@ -8,8 +8,9 @@ import (
 )
 
 var (
+	// ErrDuplicateOrOutOfOrderAck occurs when a duplicate or an out-of-order ACK is received
+	ErrDuplicateOrOutOfOrderAck = errors.New("SentPacketHandler: Duplicate or out-of-order ACK")
 	errAckForUnsentPacket       = errors.New("SentPacketHandler: Received ACK for an unsent package")
-	errDuplicateOrOutOfOrderAck = errors.New("SentPacketHandler: Duplicate or out-of-order ACK")
 	errEntropy                  = errors.New("SentPacketHandler: Wrong entropy")
 	errMapAccess                = errors.New("SentPacketHandler: Packet does not exist in PacketHistory")
 	retransmissionThreshold     = uint8(3)
@@ -119,7 +120,7 @@ func (h *sentPacketHandler) ReceivedAck(ackFrame *frames.AckFrame) error {
 	}
 
 	if ackFrame.LargestObserved <= h.LargestObserved { // duplicate or out-of-order AckFrame
-		return errDuplicateOrOutOfOrderAck
+		return ErrDuplicateOrOutOfOrderAck
 	}
 
 	expectedEntropy, err := h.calculateExpectedEntropy(ackFrame)
diff --git a/ackhandler/sent_packet_handler_test.go b/ackhandler/sent_packet_handler_test.go
index c3350d801..d67691ec9 100644
--- a/ackhandler/sent_packet_handler_test.go
+++ b/ackhandler/sent_packet_handler_test.go
@@ -249,7 +249,7 @@ var _ = Describe("SentPacketHandler", func() {
 				Expect(err).ToNot(HaveOccurred())
 				err = handler.ReceivedAck(&ack)
 				Expect(err).To(HaveOccurred())
-				Expect(err).To(Equal(errDuplicateOrOutOfOrderAck))
+				Expect(err).To(Equal(ErrDuplicateOrOutOfOrderAck))
 			})
 
 			It("rejects out of order ACKs", func() {
@@ -262,7 +262,7 @@ var _ = Describe("SentPacketHandler", func() {
 				ack.LargestObserved--
 				err = handler.ReceivedAck(&ack)
 				Expect(err).To(HaveOccurred())
-				Expect(err).To(Equal(errDuplicateOrOutOfOrderAck))
+				Expect(err).To(Equal(ErrDuplicateOrOutOfOrderAck))
 				Expect(handler.LargestObserved).To(Equal(protocol.PacketNumber(largestObserved)))
 			})
 
diff --git a/session.go b/session.go
index 944a5c5c1..9be4324c1 100644
--- a/session.go
+++ b/session.go
@@ -75,7 +75,7 @@ func (s *Session) Run() {
 		case <-time.After(sendTimeout):
 			err = s.sendPacket()
 		}
-		if err != nil {
+		if err != nil && err != ackhandler.ErrDuplicateOrOutOfOrderAck {
 			fmt.Printf("Error in session: %s\n", err.Error())
 		}