diff --git a/internal/ackhandler/ackhandler.go b/internal/ackhandler/ackhandler.go
index 262c0156..5f50dff9 100644
--- a/internal/ackhandler/ackhandler.go
+++ b/internal/ackhandler/ackhandler.go
@@ -1,7 +1,6 @@
 package ackhandler
 
 import (
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/logging"
@@ -11,7 +10,7 @@ import (
 // NewAckHandler creates a new SentPacketHandler and a new ReceivedPacketHandler
 func NewAckHandler(
 	initialPacketNumber protocol.PacketNumber,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	pers protocol.Perspective,
 	traceCallback func(quictrace.Event),
 	tracer logging.ConnectionTracer,
diff --git a/internal/ackhandler/received_packet_handler.go b/internal/ackhandler/received_packet_handler.go
index 1b707639..fc74ba2b 100644
--- a/internal/ackhandler/received_packet_handler.go
+++ b/internal/ackhandler/received_packet_handler.go
@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/internal/wire"
@@ -45,7 +44,7 @@ var _ ReceivedPacketHandler = &receivedPacketHandler{}
 
 func newReceivedPacketHandler(
 	sentPackets sentPacketTracker,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	logger utils.Logger,
 	version protocol.VersionNumber,
 ) ReceivedPacketHandler {
diff --git a/internal/ackhandler/received_packet_handler_test.go b/internal/ackhandler/received_packet_handler_test.go
index 7fbf2119..e3f4bd64 100644
--- a/internal/ackhandler/received_packet_handler_test.go
+++ b/internal/ackhandler/received_packet_handler_test.go
@@ -5,7 +5,6 @@ import (
 
 	"github.com/golang/mock/gomock"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/internal/wire"
@@ -22,7 +21,7 @@ var _ = Describe("Received Packet Handler", func() {
 		sentPackets = NewMockSentPacketTracker(mockCtrl)
 		handler = newReceivedPacketHandler(
 			sentPackets,
-			&congestion.RTTStats{},
+			&utils.RTTStats{},
 			utils.DefaultLogger,
 			protocol.VersionWhatever,
 		)
diff --git a/internal/ackhandler/received_packet_tracker.go b/internal/ackhandler/received_packet_tracker.go
index c6fc57c9..3f4310e5 100644
--- a/internal/ackhandler/received_packet_tracker.go
+++ b/internal/ackhandler/received_packet_tracker.go
@@ -3,7 +3,6 @@ package ackhandler
 import (
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/internal/wire"
@@ -17,7 +16,7 @@ type receivedPacketTracker struct {
 	packetHistory *receivedPacketHistory
 
 	maxAckDelay time.Duration
-	rttStats    *congestion.RTTStats
+	rttStats    *utils.RTTStats
 
 	hasNewAck bool // true as soon as we received an ack-eliciting new packet
 	ackQueued bool // true once we received more than 2 (or later in the connection 10) ack-eliciting packets
@@ -32,7 +31,7 @@ type receivedPacketTracker struct {
 }
 
 func newReceivedPacketTracker(
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	logger utils.Logger,
 	version protocol.VersionNumber,
 ) *receivedPacketTracker {
diff --git a/internal/ackhandler/received_packet_tracker_test.go b/internal/ackhandler/received_packet_tracker_test.go
index fab8c700..7de9cda4 100644
--- a/internal/ackhandler/received_packet_tracker_test.go
+++ b/internal/ackhandler/received_packet_tracker_test.go
@@ -3,7 +3,6 @@ package ackhandler
 import (
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/internal/wire"
@@ -15,11 +14,11 @@ import (
 var _ = Describe("Received Packet Tracker", func() {
 	var (
 		tracker  *receivedPacketTracker
-		rttStats *congestion.RTTStats
+		rttStats *utils.RTTStats
 	)
 
 	BeforeEach(func() {
-		rttStats = &congestion.RTTStats{}
+		rttStats = &utils.RTTStats{}
 		tracker = newReceivedPacketTracker(rttStats, utils.DefaultLogger, protocol.VersionWhatever)
 	})
 
diff --git a/internal/ackhandler/sent_packet_handler.go b/internal/ackhandler/sent_packet_handler.go
index 58a784d7..b22cafd9 100644
--- a/internal/ackhandler/sent_packet_handler.go
+++ b/internal/ackhandler/sent_packet_handler.go
@@ -69,7 +69,7 @@ type sentPacketHandler struct {
 	bytesInFlight protocol.ByteCount
 
 	congestion congestion.SendAlgorithmWithDebugInfos
-	rttStats   *congestion.RTTStats
+	rttStats   *utils.RTTStats
 
 	// The number of times a PTO has been sent without receiving an ack.
 	ptoCount uint32
@@ -93,7 +93,7 @@ var _ sentPacketTracker = &sentPacketHandler{}
 
 func newSentPacketHandler(
 	initialPacketNumber protocol.PacketNumber,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	pers protocol.Perspective,
 	traceCallback func(quictrace.Event),
 	tracer logging.ConnectionTracer,
diff --git a/internal/ackhandler/sent_packet_handler_test.go b/internal/ackhandler/sent_packet_handler_test.go
index ee034e2d..fc0cafdd 100644
--- a/internal/ackhandler/sent_packet_handler_test.go
+++ b/internal/ackhandler/sent_packet_handler_test.go
@@ -5,7 +5,6 @@ import (
 	"time"
 
 	"github.com/golang/mock/gomock"
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/mocks"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
@@ -27,7 +26,7 @@ var _ = Describe("SentPacketHandler", func() {
 
 	JustBeforeEach(func() {
 		lostPackets = nil
-		rttStats := &congestion.RTTStats{}
+		rttStats := &utils.RTTStats{}
 		handler = newSentPacketHandler(42, rttStats, perspective, nil, nil, utils.DefaultLogger)
 		streamFrame = wire.StreamFrame{
 			StreamID: 5,
diff --git a/internal/congestion/cubic_sender.go b/internal/congestion/cubic_sender.go
index d2a3e49a..2279c331 100644
--- a/internal/congestion/cubic_sender.go
+++ b/internal/congestion/cubic_sender.go
@@ -20,7 +20,7 @@ const (
 
 type cubicSender struct {
 	hybridSlowStart HybridSlowStart
-	rttStats        *RTTStats
+	rttStats        *utils.RTTStats
 	cubic           *Cubic
 	pacer           *pacer
 	clock           Clock
@@ -63,11 +63,11 @@ var _ SendAlgorithm = &cubicSender{}
 var _ SendAlgorithmWithDebugInfos = &cubicSender{}
 
 // NewCubicSender makes a new cubic sender
-func NewCubicSender(clock Clock, rttStats *RTTStats, reno bool) *cubicSender {
+func NewCubicSender(clock Clock, rttStats *utils.RTTStats, reno bool) *cubicSender {
 	return newCubicSender(clock, rttStats, reno, initialCongestionWindow, maxCongestionWindow)
 }
 
-func newCubicSender(clock Clock, rttStats *RTTStats, reno bool, initialCongestionWindow, initialMaxCongestionWindow protocol.ByteCount) *cubicSender {
+func newCubicSender(clock Clock, rttStats *utils.RTTStats, reno bool, initialCongestionWindow, initialMaxCongestionWindow protocol.ByteCount) *cubicSender {
 	c := &cubicSender{
 		rttStats:                   rttStats,
 		largestSentPacketNumber:    protocol.InvalidPacketNumber,
diff --git a/internal/congestion/cubic_sender_test.go b/internal/congestion/cubic_sender_test.go
index 088dd158..6490a3d8 100644
--- a/internal/congestion/cubic_sender_test.go
+++ b/internal/congestion/cubic_sender_test.go
@@ -31,7 +31,7 @@ var _ = Describe("Cubic Sender", func() {
 		bytesInFlight     protocol.ByteCount
 		packetNumber      protocol.PacketNumber
 		ackedPacketNumber protocol.PacketNumber
-		rttStats          *RTTStats
+		rttStats          *utils.RTTStats
 	)
 
 	BeforeEach(func() {
@@ -39,7 +39,7 @@ var _ = Describe("Cubic Sender", func() {
 		packetNumber = 1
 		ackedPacketNumber = 0
 		clock = mockClock{}
-		rttStats = NewRTTStats()
+		rttStats = utils.NewRTTStats()
 		sender = newCubicSender(&clock, rttStats, true /*reno*/, initialCongestionWindowPackets*maxDatagramSize, MaxCongestionWindow)
 	})
 
diff --git a/internal/flowcontrol/base_flow_controller.go b/internal/flowcontrol/base_flow_controller.go
index 71acf86a..46825c42 100644
--- a/internal/flowcontrol/base_flow_controller.go
+++ b/internal/flowcontrol/base_flow_controller.go
@@ -4,7 +4,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 )
@@ -25,7 +24,7 @@ type baseFlowController struct {
 
 	epochStartTime   time.Time
 	epochStartOffset protocol.ByteCount
-	rttStats         *congestion.RTTStats
+	rttStats         *utils.RTTStats
 
 	logger utils.Logger
 }
diff --git a/internal/flowcontrol/base_flow_controller_test.go b/internal/flowcontrol/base_flow_controller_test.go
index 273b9a2b..8e20072d 100644
--- a/internal/flowcontrol/base_flow_controller_test.go
+++ b/internal/flowcontrol/base_flow_controller_test.go
@@ -5,7 +5,8 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -27,7 +28,7 @@ var _ = Describe("Base Flow controller", func() {
 
 	BeforeEach(func() {
 		controller = &baseFlowController{}
-		controller.rttStats = &congestion.RTTStats{}
+		controller.rttStats = &utils.RTTStats{}
 	})
 
 	Context("send flow control", func() {
diff --git a/internal/flowcontrol/connection_flow_controller.go b/internal/flowcontrol/connection_flow_controller.go
index 19de1c77..0c42c800 100644
--- a/internal/flowcontrol/connection_flow_controller.go
+++ b/internal/flowcontrol/connection_flow_controller.go
@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/qerr"
 	"github.com/lucas-clemente/quic-go/internal/utils"
@@ -24,7 +23,7 @@ func NewConnectionFlowController(
 	receiveWindow protocol.ByteCount,
 	maxReceiveWindow protocol.ByteCount,
 	queueWindowUpdate func(),
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	logger utils.Logger,
 ) ConnectionFlowController {
 	return &connectionFlowController{
diff --git a/internal/flowcontrol/connection_flow_controller_test.go b/internal/flowcontrol/connection_flow_controller_test.go
index e03cbf07..4dc1b692 100644
--- a/internal/flowcontrol/connection_flow_controller_test.go
+++ b/internal/flowcontrol/connection_flow_controller_test.go
@@ -3,7 +3,6 @@ package flowcontrol
 import (
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	. "github.com/onsi/ginkgo"
@@ -25,13 +24,13 @@ var _ = Describe("Connection Flow controller", func() {
 	BeforeEach(func() {
 		queuedWindowUpdate = false
 		controller = &connectionFlowController{}
-		controller.rttStats = &congestion.RTTStats{}
+		controller.rttStats = &utils.RTTStats{}
 		controller.logger = utils.DefaultLogger
 		controller.queueWindowUpdate = func() { queuedWindowUpdate = true }
 	})
 
 	Context("Constructor", func() {
-		rttStats := &congestion.RTTStats{}
+		rttStats := &utils.RTTStats{}
 
 		It("sets the send and receive windows", func() {
 			receiveWindow := protocol.ByteCount(2000)
diff --git a/internal/flowcontrol/stream_flow_controller.go b/internal/flowcontrol/stream_flow_controller.go
index 26460e8c..90b04e72 100644
--- a/internal/flowcontrol/stream_flow_controller.go
+++ b/internal/flowcontrol/stream_flow_controller.go
@@ -3,7 +3,6 @@ package flowcontrol
 import (
 	"fmt"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/qerr"
 	"github.com/lucas-clemente/quic-go/internal/utils"
@@ -31,7 +30,7 @@ func NewStreamFlowController(
 	maxReceiveWindow protocol.ByteCount,
 	initialSendWindow protocol.ByteCount,
 	queueWindowUpdate func(protocol.StreamID),
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	logger utils.Logger,
 ) StreamFlowController {
 	return &streamFlowController{
diff --git a/internal/flowcontrol/stream_flow_controller_test.go b/internal/flowcontrol/stream_flow_controller_test.go
index cfb26655..fca80949 100644
--- a/internal/flowcontrol/stream_flow_controller_test.go
+++ b/internal/flowcontrol/stream_flow_controller_test.go
@@ -3,7 +3,6 @@ package flowcontrol
 import (
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	. "github.com/onsi/ginkgo"
@@ -18,7 +17,7 @@ var _ = Describe("Stream Flow controller", func() {
 
 	BeforeEach(func() {
 		queuedWindowUpdate = false
-		rttStats := &congestion.RTTStats{}
+		rttStats := &utils.RTTStats{}
 		controller = &streamFlowController{
 			streamID:   10,
 			connection: NewConnectionFlowController(1000, 1000, func() {}, rttStats, utils.DefaultLogger).(*connectionFlowController),
@@ -30,7 +29,7 @@ var _ = Describe("Stream Flow controller", func() {
 	})
 
 	Context("Constructor", func() {
-		rttStats := &congestion.RTTStats{}
+		rttStats := &utils.RTTStats{}
 		receiveWindow := protocol.ByteCount(2000)
 		maxReceiveWindow := protocol.ByteCount(3000)
 		sendWindow := protocol.ByteCount(4000)
diff --git a/internal/handshake/crypto_setup.go b/internal/handshake/crypto_setup.go
index d2ce23a6..04cab43c 100644
--- a/internal/handshake/crypto_setup.go
+++ b/internal/handshake/crypto_setup.go
@@ -10,7 +10,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/qerr"
 	"github.com/lucas-clemente/quic-go/internal/utils"
@@ -92,7 +91,7 @@ type cryptoSetup struct {
 	// for clients: to see if a ServerHello is a HelloRetryRequest
 	writeRecord chan struct{}
 
-	rttStats *congestion.RTTStats
+	rttStats *utils.RTTStats
 
 	tracer logging.ConnectionTracer
 	logger utils.Logger
@@ -136,7 +135,7 @@ func NewCryptoSetupClient(
 	runner handshakeRunner,
 	tlsConf *tls.Config,
 	enable0RTT bool,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	tracer logging.ConnectionTracer,
 	logger utils.Logger,
 ) (CryptoSetup, <-chan *wire.TransportParameters /* ClientHello written. Receive nil for non-0-RTT */) {
@@ -168,7 +167,7 @@ func NewCryptoSetupServer(
 	runner handshakeRunner,
 	tlsConf *tls.Config,
 	enable0RTT bool,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	tracer logging.ConnectionTracer,
 	logger utils.Logger,
 ) CryptoSetup {
@@ -197,7 +196,7 @@ func newCryptoSetup(
 	runner handshakeRunner,
 	tlsConf *tls.Config,
 	enable0RTT bool,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	tracer logging.ConnectionTracer,
 	logger utils.Logger,
 	perspective protocol.Perspective,
diff --git a/internal/handshake/crypto_setup_test.go b/internal/handshake/crypto_setup_test.go
index 3bf8f826..2b085c67 100644
--- a/internal/handshake/crypto_setup_test.go
+++ b/internal/handshake/crypto_setup_test.go
@@ -11,7 +11,6 @@ import (
 	"math/big"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/qerr"
 	"github.com/lucas-clemente/quic-go/internal/testdata"
@@ -99,7 +98,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			NewMockHandshakeRunner(mockCtrl),
 			tlsConf,
 			false,
-			&congestion.RTTStats{},
+			&utils.RTTStats{},
 			nil,
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -133,7 +132,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			runner,
 			testdata.GetTLSConfig(),
 			false,
-			&congestion.RTTStats{},
+			&utils.RTTStats{},
 			nil,
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -173,7 +172,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			runner,
 			testdata.GetTLSConfig(),
 			false,
-			&congestion.RTTStats{},
+			&utils.RTTStats{},
 			nil,
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -216,7 +215,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			runner,
 			serverConf,
 			false,
-			&congestion.RTTStats{},
+			&utils.RTTStats{},
 			nil,
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -252,7 +251,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			NewMockHandshakeRunner(mockCtrl),
 			serverConf,
 			false,
-			&congestion.RTTStats{},
+			&utils.RTTStats{},
 			nil,
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -287,8 +286,8 @@ var _ = Describe("Crypto Setup TLS", func() {
 			}
 		}
 
-		newRTTStatsWithRTT := func(rtt time.Duration) *congestion.RTTStats {
-			rttStats := &congestion.RTTStats{}
+		newRTTStatsWithRTT := func(rtt time.Duration) *utils.RTTStats {
+			rttStats := &utils.RTTStats{}
 			rttStats.UpdateRTT(rtt, 0, time.Now())
 			ExpectWithOffset(1, rttStats.SmoothedRTT()).To(Equal(rtt))
 			return rttStats
@@ -328,7 +327,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 
 		handshakeWithTLSConf := func(
 			clientConf, serverConf *tls.Config,
-			clientRTTStats, serverRTTStats *congestion.RTTStats,
+			clientRTTStats, serverRTTStats *utils.RTTStats,
 			clientTransportParameters, serverTransportParameters *wire.TransportParameters,
 			enable0RTT bool,
 		) (<-chan *wire.TransportParameters /* clientHelloWrittenChan */, CryptoSetup /* client */, error /* client error */, CryptoSetup /* server */, error /* server error */) {
@@ -399,7 +398,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 		It("handshakes", func() {
 			_, _, clientErr, _, serverErr := handshakeWithTLSConf(
 				clientConf, serverConf,
-				&congestion.RTTStats{}, &congestion.RTTStats{},
+				&utils.RTTStats{}, &utils.RTTStats{},
 				&wire.TransportParameters{}, &wire.TransportParameters{},
 				false,
 			)
@@ -411,7 +410,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			serverConf.CurvePreferences = []tls.CurveID{tls.CurveP384}
 			_, _, clientErr, _, serverErr := handshakeWithTLSConf(
 				clientConf, serverConf,
-				&congestion.RTTStats{}, &congestion.RTTStats{},
+				&utils.RTTStats{}, &utils.RTTStats{},
 				&wire.TransportParameters{}, &wire.TransportParameters{},
 				false,
 			)
@@ -424,7 +423,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			serverConf.ClientAuth = qtls.RequireAnyClientCert
 			_, _, clientErr, _, serverErr := handshakeWithTLSConf(
 				clientConf, serverConf,
-				&congestion.RTTStats{}, &congestion.RTTStats{},
+				&utils.RTTStats{}, &utils.RTTStats{},
 				&wire.TransportParameters{}, &wire.TransportParameters{},
 				false,
 			)
@@ -445,7 +444,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				runner,
 				&tls.Config{InsecureSkipVerify: true},
 				false,
-				&congestion.RTTStats{},
+				&utils.RTTStats{},
 				nil,
 				utils.DefaultLogger.WithPrefix("client"),
 			)
@@ -487,7 +486,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				cRunner,
 				clientConf,
 				false,
-				&congestion.RTTStats{},
+				&utils.RTTStats{},
 				nil,
 				utils.DefaultLogger.WithPrefix("client"),
 			)
@@ -511,7 +510,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				sRunner,
 				serverConf,
 				false,
-				&congestion.RTTStats{},
+				&utils.RTTStats{},
 				nil,
 				utils.DefaultLogger.WithPrefix("server"),
 			)
@@ -544,7 +543,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 					cRunner,
 					clientConf,
 					false,
-					&congestion.RTTStats{},
+					&utils.RTTStats{},
 					nil,
 					utils.DefaultLogger.WithPrefix("client"),
 				)
@@ -564,7 +563,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 					sRunner,
 					serverConf,
 					false,
-					&congestion.RTTStats{},
+					&utils.RTTStats{},
 					nil,
 					utils.DefaultLogger.WithPrefix("server"),
 				)
@@ -604,7 +603,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 					cRunner,
 					clientConf,
 					false,
-					&congestion.RTTStats{},
+					&utils.RTTStats{},
 					nil,
 					utils.DefaultLogger.WithPrefix("client"),
 				)
@@ -624,7 +623,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 					sRunner,
 					serverConf,
 					false,
-					&congestion.RTTStats{},
+					&utils.RTTStats{},
 					nil,
 					utils.DefaultLogger.WithPrefix("server"),
 				)
@@ -661,7 +660,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				clientOrigRTTStats := newRTTStatsWithRTT(clientRTT)
 				clientHelloWrittenChan, client, clientErr, server, serverErr := handshakeWithTLSConf(
 					clientConf, serverConf,
-					clientOrigRTTStats, &congestion.RTTStats{},
+					clientOrigRTTStats, &utils.RTTStats{},
 					&wire.TransportParameters{}, &wire.TransportParameters{},
 					false,
 				)
@@ -674,10 +673,10 @@ var _ = Describe("Crypto Setup TLS", func() {
 
 				csc.EXPECT().Get(gomock.Any()).Return(state, true)
 				csc.EXPECT().Put(gomock.Any(), gomock.Any()).MaxTimes(1)
-				clientRTTStats := &congestion.RTTStats{}
+				clientRTTStats := &utils.RTTStats{}
 				clientHelloWrittenChan, client, clientErr, server, serverErr = handshakeWithTLSConf(
 					clientConf, serverConf,
-					clientRTTStats, &congestion.RTTStats{},
+					clientRTTStats, &utils.RTTStats{},
 					&wire.TransportParameters{}, &wire.TransportParameters{},
 					false,
 				)
@@ -702,7 +701,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				clientConf.ClientSessionCache = csc
 				_, client, clientErr, server, serverErr := handshakeWithTLSConf(
 					clientConf, serverConf,
-					&congestion.RTTStats{}, &congestion.RTTStats{},
+					&utils.RTTStats{}, &utils.RTTStats{},
 					&wire.TransportParameters{}, &wire.TransportParameters{},
 					false,
 				)
@@ -716,7 +715,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				csc.EXPECT().Get(gomock.Any()).Return(state, true)
 				_, client, clientErr, server, serverErr = handshakeWithTLSConf(
 					clientConf, serverConf,
-					&congestion.RTTStats{}, &congestion.RTTStats{},
+					&utils.RTTStats{}, &utils.RTTStats{},
 					&wire.TransportParameters{}, &wire.TransportParameters{},
 					false,
 				)
@@ -759,8 +758,8 @@ var _ = Describe("Crypto Setup TLS", func() {
 				csc.EXPECT().Put(gomock.Any(), nil)
 				csc.EXPECT().Put(gomock.Any(), gomock.Any()).MaxTimes(1)
 
-				clientRTTStats := &congestion.RTTStats{}
-				serverRTTStats := &congestion.RTTStats{}
+				clientRTTStats := &utils.RTTStats{}
+				serverRTTStats := &utils.RTTStats{}
 				clientHelloWrittenChan, client, clientErr, server, serverErr = handshakeWithTLSConf(
 					clientConf, serverConf,
 					clientRTTStats, serverRTTStats,
@@ -797,7 +796,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				const initialMaxData protocol.ByteCount = 1337
 				clientHelloWrittenChan, client, clientErr, server, serverErr := handshakeWithTLSConf(
 					clientConf, serverConf,
-					clientOrigRTTStats, &congestion.RTTStats{},
+					clientOrigRTTStats, &utils.RTTStats{},
 					&wire.TransportParameters{}, &wire.TransportParameters{InitialMaxData: initialMaxData},
 					true,
 				)
@@ -812,10 +811,10 @@ var _ = Describe("Crypto Setup TLS", func() {
 				csc.EXPECT().Put(gomock.Any(), nil)
 				csc.EXPECT().Put(gomock.Any(), gomock.Any()).MaxTimes(1)
 
-				clientRTTStats := &congestion.RTTStats{}
+				clientRTTStats := &utils.RTTStats{}
 				clientHelloWrittenChan, client, clientErr, server, serverErr = handshakeWithTLSConf(
 					clientConf, serverConf,
-					clientRTTStats, &congestion.RTTStats{},
+					clientRTTStats, &utils.RTTStats{},
 					&wire.TransportParameters{}, &wire.TransportParameters{InitialMaxData: initialMaxData + 1},
 					true,
 				)
diff --git a/internal/handshake/qtls.go b/internal/handshake/qtls.go
index a0508277..7a5bc274 100644
--- a/internal/handshake/qtls.go
+++ b/internal/handshake/qtls.go
@@ -6,9 +6,9 @@ import (
 	"time"
 	"unsafe"
 
-	"github.com/marten-seemann/qtls"
+	"github.com/lucas-clemente/quic-go/internal/utils"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
+	"github.com/marten-seemann/qtls"
 )
 
 func init() {
@@ -46,7 +46,7 @@ func tlsConfigToQtlsConfig(
 	c *tls.Config,
 	recordLayer qtls.RecordLayer,
 	extHandler tlsExtensionHandler,
-	rttStats *congestion.RTTStats,
+	rttStats *utils.RTTStats,
 	getDataForSessionState func() []byte,
 	setDataFromSessionState func([]byte),
 	accept0RTT func([]byte) bool,
diff --git a/internal/handshake/qtls_test.go b/internal/handshake/qtls_test.go
index 2733c0f2..fe83dc57 100644
--- a/internal/handshake/qtls_test.go
+++ b/internal/handshake/qtls_test.go
@@ -6,7 +6,8 @@ import (
 	"net"
 	"unsafe"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+
 	"github.com/marten-seemann/qtls"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -30,19 +31,19 @@ func (*mockExtensionHandler) TransportParameters() <-chan []byte { panic("not im
 var _ = Describe("qtls.Config", func() {
 	It("sets MinVersion and MaxVersion", func() {
 		tlsConf := &tls.Config{MinVersion: tls.VersionTLS11, MaxVersion: tls.VersionTLS12}
-		qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+		qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 		Expect(qtlsConf.MinVersion).To(BeEquivalentTo(tls.VersionTLS13))
 		Expect(qtlsConf.MaxVersion).To(BeEquivalentTo(tls.VersionTLS13))
 	})
 
 	It("works when called with a nil config", func() {
-		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 		Expect(qtlsConf).ToNot(BeNil())
 	})
 
 	It("sets the setter and getter function for TLS extensions", func() {
 		extHandler := &mockExtensionHandler{}
-		qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, extHandler, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+		qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, extHandler, utils.NewRTTStats(), nil, nil, nil, nil, false)
 		Expect(extHandler.get).To(BeFalse())
 		qtlsConf.GetExtensions(10)
 		Expect(extHandler.get).To(BeTrue())
@@ -53,7 +54,7 @@ var _ = Describe("qtls.Config", func() {
 
 	It("sets the Accept0RTT callback", func() {
 		accept0RTT := func([]byte) bool { return true }
-		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, accept0RTT, nil, false)
+		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, accept0RTT, nil, false)
 		Expect(qtlsConf.Accept0RTT).ToNot(BeNil())
 		Expect(qtlsConf.Accept0RTT(nil)).To(BeTrue())
 	})
@@ -61,32 +62,32 @@ var _ = Describe("qtls.Config", func() {
 	It("sets the Accept0RTT callback", func() {
 		var called bool
 		rejected0RTT := func() { called = true }
-		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, rejected0RTT, false)
+		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, rejected0RTT, false)
 		Expect(qtlsConf.Rejected0RTT).ToNot(BeNil())
 		qtlsConf.Rejected0RTT()
 		Expect(called).To(BeTrue())
 	})
 
 	It("enables 0-RTT", func() {
-		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+		qtlsConf := tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 		Expect(qtlsConf.Enable0RTT).To(BeFalse())
 		Expect(qtlsConf.MaxEarlyData).To(BeZero())
-		qtlsConf = tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, true)
+		qtlsConf = tlsConfigToQtlsConfig(nil, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, true)
 		Expect(qtlsConf.Enable0RTT).To(BeTrue())
 		Expect(qtlsConf.MaxEarlyData).To(Equal(uint32(0xffffffff)))
 	})
 
 	It("initializes such that the session ticket key remains constant", func() {
 		tlsConf := &tls.Config{}
-		qtlsConf1 := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
-		qtlsConf2 := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+		qtlsConf1 := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
+		qtlsConf2 := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 		Expect(qtlsConf1.SessionTicketKey).ToNot(BeZero()) // should now contain a random value
 		Expect(qtlsConf1.SessionTicketKey).To(Equal(qtlsConf2.SessionTicketKey))
 	})
 
 	Context("GetConfigForClient callback", func() {
 		It("doesn't set it if absent", func() {
-			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			Expect(qtlsConf.GetConfigForClient).To(BeNil())
 		})
 
@@ -97,7 +98,7 @@ var _ = Describe("qtls.Config", func() {
 				},
 			}
 			extHandler := &mockExtensionHandler{}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, extHandler, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, extHandler, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			Expect(qtlsConf.GetConfigForClient).ToNot(BeNil())
 			confForClient, err := qtlsConf.GetConfigForClient(nil)
 			Expect(err).ToNot(HaveOccurred())
@@ -117,7 +118,7 @@ var _ = Describe("qtls.Config", func() {
 					return nil, testErr
 				},
 			}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			_, err := qtlsConf.GetConfigForClient(nil)
 			Expect(err).To(MatchError(testErr))
 		})
@@ -128,7 +129,7 @@ var _ = Describe("qtls.Config", func() {
 					return nil, nil
 				},
 			}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			Expect(qtlsConf.GetConfigForClient(nil)).To(BeNil())
 		})
 	})
@@ -140,7 +141,7 @@ var _ = Describe("qtls.Config", func() {
 					return &tls.Certificate{Certificate: [][]byte{[]byte("foo"), []byte("bar")}}, nil
 				},
 			}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			qtlsCert, err := qtlsConf.GetCertificate(nil)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(qtlsCert).ToNot(BeNil())
@@ -148,7 +149,7 @@ var _ = Describe("qtls.Config", func() {
 		})
 
 		It("doesn't set it if absent", func() {
-			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			Expect(qtlsConf.GetCertificate).To(BeNil())
 		})
 
@@ -158,7 +159,7 @@ var _ = Describe("qtls.Config", func() {
 					return nil, errors.New("test")
 				},
 			}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			_, err := qtlsConf.GetCertificate(nil)
 			Expect(err).To(MatchError("test"))
 		})
@@ -169,21 +170,21 @@ var _ = Describe("qtls.Config", func() {
 					return nil, nil
 				},
 			}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			Expect(qtlsConf.GetCertificate(nil)).To(BeNil())
 		})
 	})
 
 	Context("ClientSessionCache", func() {
 		It("doesn't set if absent", func() {
-			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(&tls.Config{}, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			Expect(qtlsConf.ClientSessionCache).To(BeNil())
 		})
 
 		It("puts a nil session state", func() {
 			csc := NewMockClientSessionCache(mockCtrl)
 			tlsConf := &tls.Config{ClientSessionCache: csc}
-			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, congestion.NewRTTStats(), nil, nil, nil, nil, false)
+			qtlsConf := tlsConfigToQtlsConfig(tlsConf, nil, &mockExtensionHandler{}, utils.NewRTTStats(), nil, nil, nil, nil, false)
 			// put something
 			csc.EXPECT().Put("foobar", nil)
 			qtlsConf.ClientSessionCache.Put("foobar", nil)
diff --git a/internal/handshake/updatable_aead.go b/internal/handshake/updatable_aead.go
index 2da4d9c5..11c0accb 100644
--- a/internal/handshake/updatable_aead.go
+++ b/internal/handshake/updatable_aead.go
@@ -9,7 +9,6 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/qerr"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/lucas-clemente/quic-go/logging"
@@ -72,7 +71,7 @@ type updatableAEAD struct {
 	headerDecrypter headerProtector
 	headerEncrypter headerProtector
 
-	rttStats *congestion.RTTStats
+	rttStats *utils.RTTStats
 
 	tracer logging.ConnectionTracer
 	logger utils.Logger
@@ -84,7 +83,7 @@ type updatableAEAD struct {
 var _ ShortHeaderOpener = &updatableAEAD{}
 var _ ShortHeaderSealer = &updatableAEAD{}
 
-func newUpdatableAEAD(rttStats *congestion.RTTStats, tracer logging.ConnectionTracer, logger utils.Logger) *updatableAEAD {
+func newUpdatableAEAD(rttStats *utils.RTTStats, tracer logging.ConnectionTracer, logger utils.Logger) *updatableAEAD {
 	return &updatableAEAD{
 		firstPacketNumber:       protocol.InvalidPacketNumber,
 		largestAcked:            protocol.InvalidPacketNumber,
diff --git a/internal/handshake/updatable_aead_test.go b/internal/handshake/updatable_aead_test.go
index f48f6370..013b9ff6 100644
--- a/internal/handshake/updatable_aead_test.go
+++ b/internal/handshake/updatable_aead_test.go
@@ -6,7 +6,6 @@ import (
 	"os"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	"github.com/marten-seemann/qtls"
@@ -18,7 +17,7 @@ import (
 var _ = Describe("Updatable AEAD", func() {
 	It("ChaCha test vector from the draft", func() {
 		secret := splitHexString("9ac312a7f877468ebe69422748ad00a1 5443f18203a07d6060f688f30f21632b")
-		aead := newUpdatableAEAD(&congestion.RTTStats{}, nil, nil)
+		aead := newUpdatableAEAD(&utils.RTTStats{}, nil, nil)
 		chacha := cipherSuites[2]
 		Expect(chacha.ID).To(Equal(qtls.TLS_CHACHA20_POLY1305_SHA256))
 		aead.SetWriteKey(chacha, secret)
@@ -37,7 +36,7 @@ var _ = Describe("Updatable AEAD", func() {
 		cs := cipherSuites[i]
 
 		Context(fmt.Sprintf("using %s", qtls.CipherSuiteName(cs.ID)), func() {
-			getPeers := func(rttStats *congestion.RTTStats) (client, server *updatableAEAD) {
+			getPeers := func(rttStats *utils.RTTStats) (client, server *updatableAEAD) {
 				trafficSecret1 := make([]byte, 16)
 				trafficSecret2 := make([]byte, 16)
 				rand.Read(trafficSecret1)
@@ -54,7 +53,7 @@ var _ = Describe("Updatable AEAD", func() {
 
 			Context("header protection", func() {
 				It("encrypts and decrypts the header", func() {
-					server, client := getPeers(&congestion.RTTStats{})
+					server, client := getPeers(&utils.RTTStats{})
 					var lastFiveBitsDifferent int
 					for i := 0; i < 100; i++ {
 						sample := make([]byte, 16)
@@ -77,10 +76,10 @@ var _ = Describe("Updatable AEAD", func() {
 			Context("message encryption", func() {
 				var msg, ad []byte
 				var server, client *updatableAEAD
-				var rttStats *congestion.RTTStats
+				var rttStats *utils.RTTStats
 
 				BeforeEach(func() {
-					rttStats = &congestion.RTTStats{}
+					rttStats = &utils.RTTStats{}
 					server, client = getPeers(rttStats)
 					msg = []byte("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.")
 					ad = []byte("Donec in velit neque.")
diff --git a/internal/mocks/connection_tracer.go b/internal/mocks/connection_tracer.go
index 73e63d8b..5581db74 100644
--- a/internal/mocks/connection_tracer.go
+++ b/internal/mocks/connection_tracer.go
@@ -5,15 +5,16 @@
 package mocks
 
 import (
-	net "net"
-	reflect "reflect"
-	time "time"
+	"net"
+	"reflect"
+	"time"
 
-	gomock "github.com/golang/mock/gomock"
-	congestion "github.com/lucas-clemente/quic-go/internal/congestion"
-	protocol "github.com/lucas-clemente/quic-go/internal/protocol"
-	wire "github.com/lucas-clemente/quic-go/internal/wire"
-	logging "github.com/lucas-clemente/quic-go/logging"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+
+	"github.com/golang/mock/gomock"
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/wire"
+	"github.com/lucas-clemente/quic-go/logging"
 )
 
 // MockConnectionTracer is a mock of ConnectionTracer interface
@@ -256,7 +257,7 @@ func (mr *MockConnectionTracerMockRecorder) UpdatedKeyFromTLS(arg0, arg1 interfa
 }
 
 // UpdatedMetrics mocks base method
-func (m *MockConnectionTracer) UpdatedMetrics(arg0 *congestion.RTTStats, arg1, arg2 protocol.ByteCount, arg3 int) {
+func (m *MockConnectionTracer) UpdatedMetrics(arg0 *utils.RTTStats, arg1, arg2 protocol.ByteCount, arg3 int) {
 	m.ctrl.T.Helper()
 	m.ctrl.Call(m, "UpdatedMetrics", arg0, arg1, arg2, arg3)
 }
diff --git a/internal/congestion/rtt_stats.go b/internal/utils/rtt_stats.go
similarity index 87%
rename from internal/congestion/rtt_stats.go
rename to internal/utils/rtt_stats.go
index 2021f7de..66642ba8 100644
--- a/internal/congestion/rtt_stats.go
+++ b/internal/utils/rtt_stats.go
@@ -1,10 +1,9 @@
-package congestion
+package utils
 
 import (
 	"time"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
-	"github.com/lucas-clemente/quic-go/internal/utils"
 )
 
 const (
@@ -56,7 +55,7 @@ func (r *RTTStats) PTO(includeMaxAckDelay bool) time.Duration {
 	if r.SmoothedRTT() == 0 {
 		return 2 * defaultInitialRTT
 	}
-	pto := r.SmoothedRTT() + utils.MaxDuration(4*r.MeanDeviation(), protocol.TimerGranularity)
+	pto := r.SmoothedRTT() + MaxDuration(4*r.MeanDeviation(), protocol.TimerGranularity)
 	if includeMaxAckDelay {
 		pto += r.MaxAckDelay()
 	}
@@ -65,7 +64,7 @@ func (r *RTTStats) PTO(includeMaxAckDelay bool) time.Duration {
 
 // UpdateRTT updates the RTT based on a new sample.
 func (r *RTTStats) UpdateRTT(sendDelta, ackDelay time.Duration, now time.Time) {
-	if sendDelta == utils.InfDuration || sendDelta <= 0 {
+	if sendDelta == InfDuration || sendDelta <= 0 {
 		return
 	}
 
@@ -91,7 +90,7 @@ func (r *RTTStats) UpdateRTT(sendDelta, ackDelay time.Duration, now time.Time) {
 		r.smoothedRTT = sample
 		r.meanDeviation = sample / 2
 	} else {
-		r.meanDeviation = time.Duration(oneMinusBeta*float32(r.meanDeviation/time.Microsecond)+rttBeta*float32(utils.AbsDuration(r.smoothedRTT-sample)/time.Microsecond)) * time.Microsecond
+		r.meanDeviation = time.Duration(oneMinusBeta*float32(r.meanDeviation/time.Microsecond)+rttBeta*float32(AbsDuration(r.smoothedRTT-sample)/time.Microsecond)) * time.Microsecond
 		r.smoothedRTT = time.Duration((float32(r.smoothedRTT/time.Microsecond)*oneMinusAlpha)+(float32(sample/time.Microsecond)*rttAlpha)) * time.Microsecond
 	}
 }
@@ -123,6 +122,6 @@ func (r *RTTStats) OnConnectionMigration() {
 // is larger. The mean deviation is increased to the most recent deviation if
 // it's larger.
 func (r *RTTStats) ExpireSmoothedMetrics() {
-	r.meanDeviation = utils.MaxDuration(r.meanDeviation, utils.AbsDuration(r.smoothedRTT-r.latestRTT))
-	r.smoothedRTT = utils.MaxDuration(r.smoothedRTT, r.latestRTT)
+	r.meanDeviation = MaxDuration(r.meanDeviation, AbsDuration(r.smoothedRTT-r.latestRTT))
+	r.smoothedRTT = MaxDuration(r.smoothedRTT, r.latestRTT)
 }
diff --git a/internal/congestion/rtt_stats_test.go b/internal/utils/rtt_stats_test.go
similarity index 98%
rename from internal/congestion/rtt_stats_test.go
rename to internal/utils/rtt_stats_test.go
index 88cc2528..7a29518c 100644
--- a/internal/congestion/rtt_stats_test.go
+++ b/internal/utils/rtt_stats_test.go
@@ -1,10 +1,10 @@
-package congestion
+package utils
 
 import (
 	"time"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
-	"github.com/lucas-clemente/quic-go/internal/utils"
+
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 )
@@ -113,7 +113,7 @@ var _ = Describe("RTT stats", func() {
 
 		badSendDeltas := []time.Duration{
 			0,
-			utils.InfDuration,
+			InfDuration,
 			-1000 * time.Microsecond,
 		}
 		// log.StartCapturingLogs();
diff --git a/logging/interface.go b/logging/interface.go
index d5d251c4..8db05b90 100644
--- a/logging/interface.go
+++ b/logging/interface.go
@@ -6,7 +6,8 @@ import (
 	"net"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/qerr"
 	"github.com/lucas-clemente/quic-go/internal/wire"
@@ -49,7 +50,7 @@ type (
 	ApplicationError = qerr.ErrorCode
 
 	// The RTTStats contain statistics used by the congestion controller.
-	RTTStats = congestion.RTTStats
+	RTTStats = utils.RTTStats
 )
 
 const (
diff --git a/logging/mock_connection_tracer_test.go b/logging/mock_connection_tracer_test.go
index 79ab1774..8cba7d4c 100644
--- a/logging/mock_connection_tracer_test.go
+++ b/logging/mock_connection_tracer_test.go
@@ -5,13 +5,14 @@
 package logging
 
 import (
-	gomock "github.com/golang/mock/gomock"
-	congestion "github.com/lucas-clemente/quic-go/internal/congestion"
-	protocol "github.com/lucas-clemente/quic-go/internal/protocol"
-	wire "github.com/lucas-clemente/quic-go/internal/wire"
-	net "net"
-	reflect "reflect"
-	time "time"
+	"net"
+	"reflect"
+	"time"
+
+	"github.com/golang/mock/gomock"
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+	"github.com/lucas-clemente/quic-go/internal/wire"
 )
 
 // MockConnectionTracer is a mock of ConnectionTracer interface
@@ -254,7 +255,7 @@ func (mr *MockConnectionTracerMockRecorder) UpdatedKeyFromTLS(arg0, arg1 interfa
 }
 
 // UpdatedMetrics mocks base method
-func (m *MockConnectionTracer) UpdatedMetrics(arg0 *congestion.RTTStats, arg1, arg2 protocol.ByteCount, arg3 int) {
+func (m *MockConnectionTracer) UpdatedMetrics(arg0 *utils.RTTStats, arg1, arg2 protocol.ByteCount, arg3 int) {
 	m.ctrl.T.Helper()
 	m.ctrl.Call(m, "UpdatedMetrics", arg0, arg1, arg2, arg3)
 }
diff --git a/qlog/qlog.go b/qlog/qlog.go
index c3127445..6ec2eff1 100644
--- a/qlog/qlog.go
+++ b/qlog/qlog.go
@@ -9,7 +9,8 @@ import (
 	"sync"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/wire"
 	"github.com/lucas-clemente/quic-go/logging"
@@ -286,7 +287,7 @@ func (t *connectionTracer) DroppedPacket(pt logging.PacketType, size protocol.By
 	t.mutex.Unlock()
 }
 
-func (t *connectionTracer) UpdatedMetrics(rttStats *congestion.RTTStats, cwnd, bytesInFlight protocol.ByteCount, packetsInFlight int) {
+func (t *connectionTracer) UpdatedMetrics(rttStats *utils.RTTStats, cwnd, bytesInFlight protocol.ByteCount, packetsInFlight int) {
 	m := &metrics{
 		MinRTT:           rttStats.MinRTT(),
 		SmoothedRTT:      rttStats.SmoothedRTT(),
diff --git a/qlog/qlog_test.go b/qlog/qlog_test.go
index 19a241a6..0128429d 100644
--- a/qlog/qlog_test.go
+++ b/qlog/qlog_test.go
@@ -10,7 +10,8 @@ import (
 	"os"
 	"time"
 
-	"github.com/lucas-clemente/quic-go/internal/congestion"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/logging"
 
@@ -438,7 +439,7 @@ var _ = Describe("Tracing", func() {
 
 			It("records metrics updates", func() {
 				now := time.Now()
-				rttStats := congestion.NewRTTStats()
+				rttStats := utils.NewRTTStats()
 				rttStats.UpdateRTT(15*time.Millisecond, 0, now)
 				rttStats.UpdateRTT(20*time.Millisecond, 0, now)
 				rttStats.UpdateRTT(25*time.Millisecond, 0, now)
@@ -472,13 +473,13 @@ var _ = Describe("Tracing", func() {
 
 			It("only logs the diff between two metrics updates", func() {
 				now := time.Now()
-				rttStats := congestion.NewRTTStats()
+				rttStats := utils.NewRTTStats()
 				rttStats.UpdateRTT(15*time.Millisecond, 0, now)
 				rttStats.UpdateRTT(20*time.Millisecond, 0, now)
 				rttStats.UpdateRTT(25*time.Millisecond, 0, now)
 				Expect(rttStats.MinRTT()).To(Equal(15 * time.Millisecond))
 
-				rttStats2 := congestion.NewRTTStats()
+				rttStats2 := utils.NewRTTStats()
 				rttStats2.UpdateRTT(15*time.Millisecond, 0, now)
 				rttStats2.UpdateRTT(15*time.Millisecond, 0, now)
 				rttStats2.UpdateRTT(15*time.Millisecond, 0, now)
diff --git a/session.go b/session.go
index b02d0704..d25a684b 100644
--- a/session.go
+++ b/session.go
@@ -13,7 +13,6 @@ import (
 	"time"
 
 	"github.com/lucas-clemente/quic-go/internal/ackhandler"
-	"github.com/lucas-clemente/quic-go/internal/congestion"
 	"github.com/lucas-clemente/quic-go/internal/flowcontrol"
 	"github.com/lucas-clemente/quic-go/internal/handshake"
 	"github.com/lucas-clemente/quic-go/internal/logutils"
@@ -144,7 +143,7 @@ type session struct {
 	connIDManager   *connIDManager
 	connIDGenerator *connIDGenerator
 
-	rttStats *congestion.RTTStats
+	rttStats *utils.RTTStats
 
 	cryptoStreamManager   *cryptoStreamManager
 	sentPacketHandler     ackhandler.SentPacketHandler
@@ -472,7 +471,7 @@ func (s *session) preSetup() {
 	s.sendQueue = newSendQueue(s.conn)
 	s.retransmissionQueue = newRetransmissionQueue(s.version)
 	s.frameParser = wire.NewFrameParser(s.version)
-	s.rttStats = &congestion.RTTStats{}
+	s.rttStats = &utils.RTTStats{}
 	s.connFlowController = flowcontrol.NewConnectionFlowController(
 		protocol.InitialMaxData,
 		protocol.ByteCount(s.config.MaxReceiveConnectionFlowControlWindow),