diff --git a/internal/congestion/cubic_sender.go b/internal/congestion/cubic_sender.go
index 2f372044..074ed667 100644
--- a/internal/congestion/cubic_sender.go
+++ b/internal/congestion/cubic_sender.go
@@ -10,12 +10,12 @@ import (
 const (
 	// maxDatagramSize is the default maximum packet size used in the Linux TCP implementation.
 	// Used in QUIC for congestion window computations in bytes.
-	maxDatagramSize         protocol.ByteCount = 1460
-	maxBurstBytes                              = 3 * maxDatagramSize
-	renoBeta                float32            = 0.7 // Reno backoff factor.
-	maxCongestionWindow                        = protocol.MaxCongestionWindowPackets * maxDatagramSize
-	minCongestionWindow                        = 2 * maxDatagramSize
-	initialCongestionWindow                    = 32 * maxDatagramSize
+	maxDatagramSize                 = protocol.ByteCount(protocol.MaxPacketSizeIPv4)
+	maxBurstBytes                   = 3 * maxDatagramSize
+	renoBeta                float32 = 0.7 // Reno backoff factor.
+	maxCongestionWindow             = protocol.MaxCongestionWindowPackets * maxDatagramSize
+	minCongestionWindow             = 2 * maxDatagramSize
+	initialCongestionWindow         = 32 * maxDatagramSize
 )
 
 type cubicSender struct {
diff --git a/internal/congestion/cubic_test.go b/internal/congestion/cubic_test.go
index c9da8258..eb3b5bed 100644
--- a/internal/congestion/cubic_test.go
+++ b/internal/congestion/cubic_test.go
@@ -231,7 +231,7 @@ var _ = Describe("Cubic", func() {
 			clock.Advance(100 * time.Millisecond)
 			currentCwnd = cubic.CongestionWindowAfterAck(maxDatagramSize, currentCwnd, rttMin, clock.Now())
 		}
-		expectedCwnd = 553632
+		expectedCwnd = 553632 * maxDatagramSize / 1460
 		Expect(currentCwnd).To(Equal(expectedCwnd))
 	})
 })