diff --git a/ackhandler/interfaces.go b/ackhandler/interfaces.go
index b209b5874..94909b940 100644
--- a/ackhandler/interfaces.go
+++ b/ackhandler/interfaces.go
@@ -33,12 +33,3 @@ type ReceivedPacketHandler interface {
 
 	GetAckFrame(dequeue bool) (*frames.AckFrame, error)
 }
-
-// StopWaitingManager manages StopWaitings for sent packets
-// TODO: remove once we drop support for QUIC 33
-type StopWaitingManager interface {
-	RegisterPacketForRetransmission(packet *Packet)
-	GetStopWaitingFrame() *frames.StopWaitingFrame
-	SentStopWaitingWithPacket(packetNumber protocol.PacketNumber)
-	ReceivedAckForPacketNumber(packetNumber protocol.PacketNumber)
-}
diff --git a/packet_unpacker.go b/packet_unpacker.go
index 56e8ae679..3434751b1 100644
--- a/packet_unpacker.go
+++ b/packet_unpacker.go
@@ -98,7 +98,6 @@ ReadLoop:
 		if err != nil {
 			return nil, err
 		}
-		// TODO: Remove once all frames are implemented
 		if frame != nil {
 			fs = append(fs, frame)
 		}
diff --git a/session.go b/session.go
index f9490369e..2f380e964 100644
--- a/session.go
+++ b/session.go
@@ -52,7 +52,6 @@ type Session struct {
 
 	sentPacketHandler     ackhandler.SentPacketHandler
 	receivedPacketHandler ackhandler.ReceivedPacketHandler
-	stopWaitingManager    ackhandler.StopWaitingManager
 	streamFramer          *streamFramer
 
 	flowControlManager flowcontrol.FlowControlManager
@@ -93,7 +92,6 @@ func newSession(conn connection, v protocol.VersionNumber, connectionID protocol
 	connectionParametersManager := handshake.NewConnectionParamatersManager()
 	flowControlManager := flowcontrol.NewFlowControlManager(connectionParametersManager)
 
-	var stopWaitingManager ackhandler.StopWaitingManager
 	var sentPacketHandler ackhandler.SentPacketHandler
 	var receivedPacketHandler ackhandler.ReceivedPacketHandler
 
@@ -108,7 +106,6 @@ func newSession(conn connection, v protocol.VersionNumber, connectionID protocol
 		closeCallback:               closeCallback,
 		sentPacketHandler:           sentPacketHandler,
 		receivedPacketHandler:       receivedPacketHandler,
-		stopWaitingManager:          stopWaitingManager,
 		flowControlManager:          flowControlManager,
 		receivedPackets:             make(chan receivedPacket, protocol.MaxSessionUnprocessedPackets),
 		closeChan:                   make(chan *qerr.QuicError, 1),