diff --git a/internal/congestion/cubic_sender.go b/internal/congestion/cubic_sender.go
index 76706753..017d824c 100644
--- a/internal/congestion/cubic_sender.go
+++ b/internal/congestion/cubic_sender.go
@@ -63,7 +63,6 @@ type cubicSender struct {
 }
 
 var _ SendAlgorithm = &cubicSender{}
-var _ SendAlgorithmWithDebugInfo = &cubicSender{}
 
 // NewCubicSender makes a new cubic sender
 func NewCubicSender(clock Clock, rttStats *RTTStats, reno bool, initialCongestionWindow, initialMaxCongestionWindow protocol.ByteCount) *cubicSender {
diff --git a/internal/congestion/interface.go b/internal/congestion/interface.go
index 51e2e28d..cccbabbe 100644
--- a/internal/congestion/interface.go
+++ b/internal/congestion/interface.go
@@ -16,16 +16,3 @@ type SendAlgorithm interface {
 	OnPacketLost(number protocol.PacketNumber, lostBytes protocol.ByteCount, priorInFlight protocol.ByteCount)
 	OnRetransmissionTimeout(packetsRetransmitted bool)
 }
-
-// SendAlgorithmWithDebugInfo adds some debug functions to SendAlgorithm
-type SendAlgorithmWithDebugInfo interface {
-	SendAlgorithm
-	BandwidthEstimate() Bandwidth
-
-	// Stuff only used in testing
-
-	HybridSlowStart() *HybridSlowStart
-	SlowstartThreshold() protocol.ByteCount
-	RenoBeta() float32
-	InRecovery() bool
-}