diff --git a/frames/ack_frame.go b/frames/ack_frame.go
index af1a66e7..28c442c5 100644
--- a/frames/ack_frame.go
+++ b/frames/ack_frame.go
@@ -21,7 +21,7 @@ type AckFrame struct {
 }
 
 // Write writes an ACK frame.
-func (f *AckFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *AckFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	typeByte := uint8(0x40 | 0x0C)
 
 	if f.HasNACK() {
diff --git a/frames/ack_frame_test.go b/frames/ack_frame_test.go
index 6891b08b..ba317e2b 100644
--- a/frames/ack_frame_test.go
+++ b/frames/ack_frame_test.go
@@ -249,7 +249,7 @@ var _ = Describe("AckFrame", func() {
 				Entropy:         2,
 				LargestObserved: 1,
 			}
-			err := frame.Write(b, 1, 32)
+			err := frame.Write(b, 32)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(b.Bytes()).To(Equal([]byte{0x4c, 0x02, 0x01, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0}))
 		})
@@ -260,7 +260,7 @@ var _ = Describe("AckFrame", func() {
 				LargestObserved: 4,
 				NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 2}},
 			}
-			err := frame.Write(b, 1, 32)
+			err := frame.Write(b, 32)
 			Expect(err).ToNot(HaveOccurred())
 			missingPacketBytes := b.Bytes()[b.Len()-8:]
 			Expect(missingPacketBytes[0]).To(Equal(uint8(1))) // numRanges
@@ -276,7 +276,7 @@ var _ = Describe("AckFrame", func() {
 				LargestObserved: 4,
 				NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 2}},
 			}
-			err := frame.Write(b, 1, 31)
+			err := frame.Write(b, 31)
 			Expect(err).ToNot(HaveOccurred())
 			missingPacketBytes := b.Bytes()[b.Len()-9:]
 			Expect(missingPacketBytes[0]).To(Equal(uint8(1))) // numRanges
@@ -295,7 +295,7 @@ var _ = Describe("AckFrame", func() {
 				LargestObserved: 7,
 				NackRanges:      []NackRange{nackRange1, nackRange2},
 			}
-			err := frame.Write(b, 1, 32)
+			err := frame.Write(b, 32)
 			Expect(err).ToNot(HaveOccurred())
 			missingPacketBytes := b.Bytes()[b.Len()-(1+2*7):]
 			Expect(missingPacketBytes[0]).To(Equal(uint8(2)))      // numRanges
@@ -316,7 +316,7 @@ var _ = Describe("AckFrame", func() {
 					LargestObserved: 258,
 					NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 257}},
 				}
-				err := frame.Write(b, 1, 32)
+				err := frame.Write(b, 32)
 				Expect(err).ToNot(HaveOccurred())
 				missingPacketBytes := b.Bytes()[b.Len()-(1+7):]
 				Expect(missingPacketBytes[0]).To(Equal(uint8(1)))                   // numRanges
@@ -330,7 +330,7 @@ var _ = Describe("AckFrame", func() {
 					LargestObserved: 302,
 					NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 301}},
 				}
-				err := frame.Write(b, 1, 32)
+				err := frame.Write(b, 32)
 				Expect(err).ToNot(HaveOccurred())
 				missingPacketBytes := b.Bytes()[b.Len()-(1+2*7):]
 				Expect(missingPacketBytes[0]).To(Equal(uint8(2)))                    // numRanges
@@ -346,7 +346,7 @@ var _ = Describe("AckFrame", func() {
 					LargestObserved: 259,
 					NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 258}},
 				}
-				err := frame.Write(b, 1, 32)
+				err := frame.Write(b, 32)
 				Expect(err).ToNot(HaveOccurred())
 				missingPacketBytes := b.Bytes()[b.Len()-(1+2*7):]
 				Expect(missingPacketBytes[0]).To(Equal(uint8(2)))                    // numRanges
@@ -362,7 +362,7 @@ var _ = Describe("AckFrame", func() {
 					LargestObserved: 603,
 					NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 601}},
 				}
-				err := frame.Write(b, 1, 32)
+				err := frame.Write(b, 32)
 				Expect(err).ToNot(HaveOccurred())
 				missingPacketBytes := b.Bytes()[b.Len()-(1+3*7):]
 				Expect(missingPacketBytes[0]).To(Equal(uint8(3)))                     // numRanges
@@ -382,7 +382,7 @@ var _ = Describe("AckFrame", func() {
 					LargestObserved: 655,
 					NackRanges:      []NackRange{nackRange2, nackRange1},
 				}
-				err := frame.Write(b, 1, 32)
+				err := frame.Write(b, 32)
 				Expect(err).ToNot(HaveOccurred())
 				missingPacketBytes := b.Bytes()[b.Len()-(1+4*7):]
 				Expect(missingPacketBytes[0]).To(Equal(uint8(4)))                     // numRanges
@@ -403,7 +403,7 @@ var _ = Describe("AckFrame", func() {
 					Entropy:         2,
 					LargestObserved: 1,
 				}
-				f.Write(b, 1, 2)
+				f.Write(b, 2)
 				Expect(f.MinLength()).To(Equal(protocol.ByteCount(b.Len())))
 			})
 
@@ -413,7 +413,7 @@ var _ = Describe("AckFrame", func() {
 					LargestObserved: 4,
 					NackRanges:      []NackRange{NackRange{FirstPacketNumber: 2, LastPacketNumber: 2}},
 				}
-				err := f.Write(b, 1, 31)
+				err := f.Write(b, 31)
 				Expect(err).ToNot(HaveOccurred())
 				Expect(f.MinLength()).To(Equal(protocol.ByteCount(b.Len())))
 			})
@@ -431,7 +431,7 @@ var _ = Describe("AckFrame", func() {
 				Entropy:         0xDE,
 				LargestObserved: 6789,
 			}
-			err := frameOrig.Write(b, 1, 32)
+			err := frameOrig.Write(b, 32)
 			Expect(err).ToNot(HaveOccurred())
 			frame, err := ParseAckFrame(bytes.NewReader(b.Bytes()), 32)
 			Expect(err).ToNot(HaveOccurred())
@@ -449,7 +449,7 @@ var _ = Describe("AckFrame", func() {
 				LargestObserved: 15,
 				NackRanges:      nackRanges,
 			}
-			err := frameOrig.Write(b, 1, 32)
+			err := frameOrig.Write(b, 32)
 			Expect(err).ToNot(HaveOccurred())
 			r := bytes.NewReader(b.Bytes())
 			frame, err := ParseAckFrame(r, 32)
@@ -469,7 +469,7 @@ var _ = Describe("AckFrame", func() {
 				LargestObserved: 1600,
 				NackRanges:      nackRanges,
 			}
-			err := frameOrig.Write(b, 1, 32)
+			err := frameOrig.Write(b, 32)
 			Expect(err).ToNot(HaveOccurred())
 			r := bytes.NewReader(b.Bytes())
 			frame, err := ParseAckFrame(r, 32)
diff --git a/frames/blocked_frame.go b/frames/blocked_frame.go
index e5ef653a..ddcb85b0 100644
--- a/frames/blocked_frame.go
+++ b/frames/blocked_frame.go
@@ -12,8 +12,8 @@ type BlockedFrame struct {
 	StreamID protocol.StreamID
 }
 
-//Write writes a RST_STREAM frame
-func (f *BlockedFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+//Write writes a BlockedFrame frame
+func (f *BlockedFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	b.WriteByte(0x05)
 
 	if f.StreamID == 0 {
diff --git a/frames/blocked_frame_test.go b/frames/blocked_frame_test.go
index 4299fb9e..47eb3f7a 100644
--- a/frames/blocked_frame_test.go
+++ b/frames/blocked_frame_test.go
@@ -22,7 +22,7 @@ var _ = Describe("BlockedFrame", func() {
 		It("writes a sample frame", func() {
 			b := &bytes.Buffer{}
 			frame := BlockedFrame{StreamID: 0x1337}
-			frame.Write(b, 10, 0)
+			frame.Write(b, 0)
 			Expect(b.Bytes()).To(Equal([]byte{0x05, 0x37, 0x13, 0x0, 0x0}))
 		})
 
diff --git a/frames/connection_close_frame.go b/frames/connection_close_frame.go
index 3f3a74c0..a2cc81ed 100644
--- a/frames/connection_close_frame.go
+++ b/frames/connection_close_frame.go
@@ -52,7 +52,7 @@ func (f *ConnectionCloseFrame) MinLength() (protocol.ByteCount, error) {
 }
 
 // Write writes an CONNECTION_CLOSE frame.
-func (f *ConnectionCloseFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *ConnectionCloseFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	b.WriteByte(0x02)
 	utils.WriteUint32(b, uint32(f.ErrorCode))
 
diff --git a/frames/connection_close_frame_test.go b/frames/connection_close_frame_test.go
index 91a00755..8ad883b2 100644
--- a/frames/connection_close_frame_test.go
+++ b/frames/connection_close_frame_test.go
@@ -35,7 +35,7 @@ var _ = Describe("ConnectionCloseFrame", func() {
 			frame := &ConnectionCloseFrame{
 				ErrorCode: 0xDEADBEEF,
 			}
-			err := frame.Write(b, 1, 0)
+			err := frame.Write(b, 0)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(b.Len()).To(Equal(1 + 2 + 4))
 			Expect(b.Bytes()).To(Equal([]byte{0x02, 0xEF, 0xBE, 0xAD, 0xDE, 0x00, 0x00}))
@@ -47,7 +47,7 @@ var _ = Describe("ConnectionCloseFrame", func() {
 				ErrorCode:    0xDEADBEEF,
 				ReasonPhrase: "foobar",
 			}
-			err := frame.Write(b, 1, 0)
+			err := frame.Write(b, 0)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(b.Len()).To(Equal(1 + 2 + 4 + len(frame.ReasonPhrase)))
 			Expect(b.Bytes()[:5]).To(Equal([]byte{0x02, 0xEF, 0xBE, 0xAD, 0xDE}))
@@ -67,7 +67,7 @@ var _ = Describe("ConnectionCloseFrame", func() {
 				ErrorCode:    0xDEADBEEF,
 				ReasonPhrase: reasonPhrase,
 			}
-			err := frame.Write(b, 1, 0)
+			err := frame.Write(b, 0)
 			Expect(err).To(HaveOccurred())
 		})
 
@@ -77,7 +77,7 @@ var _ = Describe("ConnectionCloseFrame", func() {
 				ErrorCode:    0xDEADBEEF,
 				ReasonPhrase: "foobar",
 			}
-			f.Write(b, 1, 0)
+			f.Write(b, 0)
 			Expect(f.MinLength()).To(Equal(protocol.ByteCount(b.Len())))
 		})
 	})
@@ -88,7 +88,7 @@ var _ = Describe("ConnectionCloseFrame", func() {
 			ErrorCode:    0xDEADBEEF,
 			ReasonPhrase: "Lorem ipsum dolor sit amet.",
 		}
-		err := frame.Write(b, 1, 0)
+		err := frame.Write(b, 0)
 		Expect(err).ToNot(HaveOccurred())
 		readframe, err := ParseConnectionCloseFrame(bytes.NewReader(b.Bytes()))
 		Expect(err).ToNot(HaveOccurred())
diff --git a/frames/frame.go b/frames/frame.go
index e6237e59..0bed565f 100644
--- a/frames/frame.go
+++ b/frames/frame.go
@@ -8,6 +8,6 @@ import (
 
 // A Frame in QUIC
 type Frame interface {
-	Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error
+	Write(b *bytes.Buffer, version protocol.VersionNumber) error
 	MinLength() (protocol.ByteCount, error)
 }
diff --git a/frames/ping_frame.go b/frames/ping_frame.go
index 25fd5c3f..a2867f02 100644
--- a/frames/ping_frame.go
+++ b/frames/ping_frame.go
@@ -21,7 +21,7 @@ func ParsePingFrame(r *bytes.Reader) (*PingFrame, error) {
 	return frame, nil
 }
 
-func (f *PingFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *PingFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	typeByte := uint8(0x07)
 	b.WriteByte(typeByte)
 	return nil
diff --git a/frames/ping_frame_test.go b/frames/ping_frame_test.go
index 28581628..2348ca3e 100644
--- a/frames/ping_frame_test.go
+++ b/frames/ping_frame_test.go
@@ -22,7 +22,7 @@ var _ = Describe("PingFrame", func() {
 		It("writes a sample frame", func() {
 			b := &bytes.Buffer{}
 			frame := PingFrame{}
-			frame.Write(b, 10, 0)
+			frame.Write(b, 0)
 			Expect(b.Bytes()).To(Equal([]byte{0x07}))
 		})
 
diff --git a/frames/rst_stream_frame.go b/frames/rst_stream_frame.go
index 80f73d17..552494e6 100644
--- a/frames/rst_stream_frame.go
+++ b/frames/rst_stream_frame.go
@@ -15,7 +15,7 @@ type RstStreamFrame struct {
 }
 
 //Write writes a RST_STREAM frame
-func (f *RstStreamFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *RstStreamFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	panic("RstStreamFrame: Write not yet implemented")
 }
 
diff --git a/frames/stop_waiting_frame.go b/frames/stop_waiting_frame.go
index 766fc604..40e7d04b 100644
--- a/frames/stop_waiting_frame.go
+++ b/frames/stop_waiting_frame.go
@@ -13,25 +13,32 @@ type StopWaitingFrame struct {
 	LeastUnacked    protocol.PacketNumber
 	Entropy         byte
 	PacketNumberLen protocol.PacketNumberLen
+	PacketNumber    protocol.PacketNumber
 }
 
 var (
 	errLeastUnackedHigherThanPacketNumber = errors.New("StopWaitingFrame: LeastUnacked can't be greater than the packet number")
+	errPacketNumberNotSet                 = errors.New("StopWaitingFrame: PacketNumber not set")
 	errPacketNumberLenNotSet              = errors.New("StopWaitingFrame: PacketNumberLen not set")
 )
 
-func (f *StopWaitingFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *StopWaitingFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	// packetNumber is the packet number of the packet that this StopWaitingFrame will be sent with
 	typeByte := uint8(0x06)
 	b.WriteByte(typeByte)
 
 	b.WriteByte(f.Entropy)
 
-	if f.LeastUnacked > packetNumber {
+	// make sure the PacketNumber was set
+	if f.PacketNumber == protocol.PacketNumber(0) {
+		return errPacketNumberNotSet
+	}
+
+	if f.LeastUnacked > f.PacketNumber {
 		return errLeastUnackedHigherThanPacketNumber
 	}
 
-	leastUnackedDelta := uint64(packetNumber - f.LeastUnacked)
+	leastUnackedDelta := uint64(f.PacketNumber - f.LeastUnacked)
 
 	switch f.PacketNumberLen {
 	case protocol.PacketNumberLen1:
diff --git a/frames/stop_waiting_frame_test.go b/frames/stop_waiting_frame_test.go
index 13ce47a4..d390303d 100644
--- a/frames/stop_waiting_frame_test.go
+++ b/frames/stop_waiting_frame_test.go
@@ -29,25 +29,38 @@ var _ = Describe("StopWaitingFrame", func() {
 		Context("when writing", func() {
 			It("writes a sample frame", func() {
 				b := &bytes.Buffer{}
-				packetNumber := protocol.PacketNumber(13)
 				frame := &StopWaitingFrame{
 					LeastUnacked:    10,
+					PacketNumber:    13,
 					Entropy:         0xAD,
 					PacketNumberLen: protocol.PacketNumberLen6,
 				}
-				frame.Write(b, packetNumber, 0)
+				frame.Write(b, 0)
 				Expect(b.Bytes()[0]).To(Equal(uint8(0x06)))
 				Expect(b.Bytes()[1]).To(Equal(uint8(frame.Entropy)))
 				Expect(b.Bytes()[2:8]).To(Equal([]byte{3, 0, 0, 0, 0, 0}))
 			})
 
+			It("errors when PacketNumber was not set", func() {
+				b := &bytes.Buffer{}
+				frame := &StopWaitingFrame{
+					LeastUnacked:    10,
+					PacketNumberLen: protocol.PacketNumberLen1,
+					Entropy:         0xAD,
+				}
+				err := frame.Write(b, 0)
+				Expect(err).To(HaveOccurred())
+				Expect(err).To(Equal(errPacketNumberNotSet))
+			})
+
 			It("errors when PacketNumberLen was not set", func() {
 				b := &bytes.Buffer{}
 				frame := &StopWaitingFrame{
 					LeastUnacked: 10,
+					PacketNumber: 13,
 					Entropy:      0xAD,
 				}
-				err := frame.Write(b, 13, 0)
+				err := frame.Write(b, 0)
 				Expect(err).To(HaveOccurred())
 				Expect(err).To(Equal(errPacketNumberLenNotSet))
 			})
@@ -56,9 +69,10 @@ var _ = Describe("StopWaitingFrame", func() {
 				b := &bytes.Buffer{}
 				frame := &StopWaitingFrame{
 					LeastUnacked:    10,
+					PacketNumber:    5,
 					PacketNumberLen: protocol.PacketNumberLen1,
 				}
-				err := frame.Write(b, 5, 0)
+				err := frame.Write(b, 0)
 				Expect(err).To(HaveOccurred())
 				Expect(err).To(Equal(errLeastUnackedHigherThanPacketNumber))
 			})
@@ -68,9 +82,10 @@ var _ = Describe("StopWaitingFrame", func() {
 					b := &bytes.Buffer{}
 					frame := &StopWaitingFrame{
 						LeastUnacked:    10,
+						PacketNumber:    13,
 						PacketNumberLen: protocol.PacketNumberLen1,
 					}
-					frame.Write(b, 13, 0)
+					frame.Write(b, 0)
 					Expect(b.Len()).To(Equal(3))
 					Expect(b.Bytes()[2]).To(Equal(uint8(3)))
 				})
@@ -79,9 +94,10 @@ var _ = Describe("StopWaitingFrame", func() {
 					b := &bytes.Buffer{}
 					frame := &StopWaitingFrame{
 						LeastUnacked:    0x10,
+						PacketNumber:    0x1300,
 						PacketNumberLen: protocol.PacketNumberLen2,
 					}
-					frame.Write(b, 0x1300, 0)
+					frame.Write(b, 0)
 					Expect(b.Len()).To(Equal(4))
 					Expect(b.Bytes()[2:4]).To(Equal([]byte{0xF0, 0x12}))
 				})
@@ -90,9 +106,10 @@ var _ = Describe("StopWaitingFrame", func() {
 					b := &bytes.Buffer{}
 					frame := &StopWaitingFrame{
 						LeastUnacked:    0x1000,
+						PacketNumber:    0x12345678,
 						PacketNumberLen: protocol.PacketNumberLen4,
 					}
-					frame.Write(b, 0x12345678, 0)
+					frame.Write(b, 0)
 					Expect(b.Len()).To(Equal(6))
 					Expect(b.Bytes()[2:6]).To(Equal([]byte{0x78, 0x46, 0x34, 0x12}))
 				})
@@ -101,9 +118,10 @@ var _ = Describe("StopWaitingFrame", func() {
 					b := &bytes.Buffer{}
 					frame := &StopWaitingFrame{
 						LeastUnacked:    0x10,
+						PacketNumber:    0x123456789ABC,
 						PacketNumberLen: protocol.PacketNumberLen6,
 					}
-					frame.Write(b, 0x123456789ABC, 0)
+					frame.Write(b, 0)
 					Expect(b.Len()).To(Equal(8))
 					Expect(b.Bytes()[2:8]).To(Equal([]byte{0xAC, 0x9A, 0x78, 0x56, 0x34, 0x12}))
 				})
@@ -136,11 +154,12 @@ var _ = Describe("StopWaitingFrame", func() {
 				packetNumber := protocol.PacketNumber(13)
 				frame := &StopWaitingFrame{
 					LeastUnacked:    10,
+					PacketNumber:    packetNumber,
 					Entropy:         0xAC,
 					PacketNumberLen: protocol.PacketNumberLen4,
 				}
 				b := &bytes.Buffer{}
-				frame.Write(b, packetNumber, 0)
+				frame.Write(b, 0)
 				readframe, err := ParseStopWaitingFrame(bytes.NewReader(b.Bytes()), packetNumber, protocol.PacketNumberLen4)
 				Expect(err).ToNot(HaveOccurred())
 				Expect(readframe.Entropy).To(Equal(frame.Entropy))
diff --git a/frames/stream_frame.go b/frames/stream_frame.go
index 87de503a..73ed8a38 100644
--- a/frames/stream_frame.go
+++ b/frames/stream_frame.go
@@ -78,7 +78,7 @@ func ParseStreamFrame(r *bytes.Reader) (*StreamFrame, error) {
 }
 
 // WriteStreamFrame writes a stream frame.
-func (f *StreamFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *StreamFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	typeByte := uint8(0x80) // sets the leftmost bit to 1
 
 	if f.FinBit {
diff --git a/frames/stream_frame_test.go b/frames/stream_frame_test.go
index 05c3089c..962a965a 100644
--- a/frames/stream_frame_test.go
+++ b/frames/stream_frame_test.go
@@ -40,7 +40,7 @@ var _ = Describe("StreamFrame", func() {
 				StreamID:       1,
 				Data:           []byte("foobar"),
 				DataLenPresent: true,
-			}).Write(b, 1, 0)
+			}).Write(b, 0)
 			Expect(b.Bytes()).To(Equal([]byte{0xa0, 0x1, 0x06, 0x00, 'f', 'o', 'o', 'b', 'a', 'r'}))
 		})
 
@@ -51,7 +51,7 @@ var _ = Describe("StreamFrame", func() {
 				Data:     []byte("f"),
 				Offset:   0,
 			}
-			f.Write(b, 1, 0)
+			f.Write(b, 0)
 			Expect(f.MinLength()).To(Equal(protocol.ByteCount(b.Len())))
 		})
 
@@ -62,7 +62,7 @@ var _ = Describe("StreamFrame", func() {
 				Data:     []byte("f"),
 				Offset:   0xDEADBEEFCAFE,
 			}
-			f.Write(b, 1, 0)
+			f.Write(b, 0)
 			Expect(f.MinLength()).To(Equal(protocol.ByteCount(b.Len())))
 		})
 
@@ -76,7 +76,7 @@ var _ = Describe("StreamFrame", func() {
 					DataLenPresent: true,
 					Offset:         0,
 				}
-				f.Write(b, 1, 0)
+				f.Write(b, 0)
 				minLength, _ := f.MinLength()
 				headerLength := minLength - 1
 				Expect(b.Bytes()[0] & 0x20).To(Equal(uint8(0x20)))
@@ -92,7 +92,7 @@ var _ = Describe("StreamFrame", func() {
 					DataLenPresent: false,
 					Offset:         0,
 				}
-				f.Write(b, 1, 0)
+				f.Write(b, 0)
 				Expect(b.Bytes()[0] & 0x20).To(Equal(uint8(0)))
 				Expect(b.Bytes()[1 : b.Len()-dataLen]).ToNot(ContainSubstring(string([]byte{0x37, 0x13})))
 				minLength, _ := f.MinLength()
@@ -121,7 +121,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x0)))
 			})
 
@@ -131,7 +131,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0x1337,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x1 << 2)))
 				Expect(b.Bytes()[2:4]).To(Equal([]byte{0x37, 0x13}))
 			})
@@ -142,7 +142,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0x13CAFE,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x2 << 2)))
 				Expect(b.Bytes()[2:5]).To(Equal([]byte{0xFE, 0xCA, 0x13}))
 			})
@@ -153,7 +153,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0xDEADBEEF,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x3 << 2)))
 				Expect(b.Bytes()[2:6]).To(Equal([]byte{0xEF, 0xBE, 0xAD, 0xDE}))
 			})
@@ -164,7 +164,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0x13DEADBEEF,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x4 << 2)))
 				Expect(b.Bytes()[2:7]).To(Equal([]byte{0xEF, 0xBE, 0xAD, 0xDE, 0x13}))
 			})
@@ -175,7 +175,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0xDEADBEEFCAFE,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x5 << 2)))
 				Expect(b.Bytes()[2:8]).To(Equal([]byte{0xFE, 0xCA, 0xEF, 0xBE, 0xAD, 0xDE}))
 			})
@@ -186,7 +186,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0x13DEADBEEFCAFE,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x6 << 2)))
 				Expect(b.Bytes()[2:9]).To(Equal([]byte{0xFE, 0xCA, 0xEF, 0xBE, 0xAD, 0xDE, 0x13}))
 			})
@@ -197,7 +197,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID: 1,
 					Data:     []byte("foobar"),
 					Offset:   0x1337DEADBEEFCAFE,
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x1c).To(Equal(uint8(0x7 << 2)))
 				Expect(b.Bytes()[2:10]).To(Equal([]byte{0xFE, 0xCA, 0xEF, 0xBE, 0xAD, 0xDE, 0x37, 0x13}))
 			})
@@ -210,7 +210,7 @@ var _ = Describe("StreamFrame", func() {
 					StreamID:    1,
 					streamIDLen: 13,
 					Data:        []byte("foobar"),
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(err).To(HaveOccurred())
 				Expect(err).To(Equal(errInvalidStreamIDLen))
 			})
@@ -220,7 +220,7 @@ var _ = Describe("StreamFrame", func() {
 				(&StreamFrame{
 					StreamID: 13,
 					Data:     []byte("foobar"),
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x3).To(Equal(uint8(0x0)))
 				Expect(b.Bytes()[1]).To(Equal(uint8(13)))
 			})
@@ -230,7 +230,7 @@ var _ = Describe("StreamFrame", func() {
 				(&StreamFrame{
 					StreamID: 0xCAFE,
 					Data:     []byte("foobar"),
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x3).To(Equal(uint8(0x1)))
 				Expect(b.Bytes()[1:3]).To(Equal([]byte{0xFE, 0xCA}))
 			})
@@ -240,7 +240,7 @@ var _ = Describe("StreamFrame", func() {
 				(&StreamFrame{
 					StreamID: 0x13BEEF,
 					Data:     []byte("foobar"),
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x3).To(Equal(uint8(0x2)))
 				Expect(b.Bytes()[1:4]).To(Equal([]byte{0xEF, 0xBE, 0x13}))
 			})
@@ -250,7 +250,7 @@ var _ = Describe("StreamFrame", func() {
 				(&StreamFrame{
 					StreamID: 0xDECAFBAD,
 					Data:     []byte("foobar"),
-				}).Write(b, 1, 0)
+				}).Write(b, 0)
 				Expect(b.Bytes()[0] & 0x3).To(Equal(uint8(0x3)))
 				Expect(b.Bytes()[1:5]).To(Equal([]byte{0xAD, 0xFB, 0xCA, 0xDE}))
 			})
diff --git a/frames/window_update_frame.go b/frames/window_update_frame.go
index 6b96b923..5b7919d8 100644
--- a/frames/window_update_frame.go
+++ b/frames/window_update_frame.go
@@ -14,7 +14,7 @@ type WindowUpdateFrame struct {
 }
 
 //Write writes a RST_STREAM frame
-func (f *WindowUpdateFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, version protocol.VersionNumber) error {
+func (f *WindowUpdateFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
 	panic("WindowUpdateFrame: Write not yet implemented")
 }
 
diff --git a/packet_packer.go b/packet_packer.go
index 7b376e1e..9978b967 100644
--- a/packet_packer.go
+++ b/packet_packer.go
@@ -67,6 +67,7 @@ func (p *packetPacker) PackPacket(stopWaitingFrame *frames.StopWaitingFrame, con
 	}
 
 	if stopWaitingFrame != nil {
+		stopWaitingFrame.PacketNumber = currentPacketNumber
 		stopWaitingFrame.PacketNumberLen = packetNumberLen
 	}
 
@@ -112,7 +113,7 @@ func (p *packetPacker) getPayload(frames []frames.Frame, currentPacketNumber pro
 	var payload bytes.Buffer
 	payload.WriteByte(0) // The entropy bit is set in sendPayload
 	for _, frame := range frames {
-		frame.Write(&payload, currentPacketNumber, p.version)
+		frame.Write(&payload, p.version)
 	}
 	return payload.Bytes(), nil
 }
diff --git a/packet_packer_test.go b/packet_packer_test.go
index d3ae92a6..5a101e82 100644
--- a/packet_packer_test.go
+++ b/packet_packer_test.go
@@ -75,7 +75,7 @@ var _ = Describe("Packet packer", func() {
 		Expect(err).ToNot(HaveOccurred())
 		Expect(p).ToNot(BeNil())
 		b := &bytes.Buffer{}
-		f.Write(b, 1, 0)
+		f.Write(b, 0)
 		Expect(len(p.frames)).To(Equal(1))
 		Expect(p.raw).To(ContainSubstring(string(b.Bytes())))
 	})
@@ -127,7 +127,7 @@ var _ = Describe("Packet packer", func() {
 	It("packs many control frames into 1 packets", func() {
 		f := &frames.AckFrame{LargestObserved: 1}
 		b := &bytes.Buffer{}
-		f.Write(b, 3, 32)
+		f.Write(b, 32)
 		maxFramesPerPacket := int(protocol.MaxFrameAndPublicHeaderSize-publicHeaderLen) / b.Len()
 		var controlFrames []frames.Frame
 		for i := 0; i < maxFramesPerPacket; i++ {
@@ -223,9 +223,9 @@ var _ = Describe("Packet packer", func() {
 			Expect(p).ToNot(BeNil())
 			Expect(err).ToNot(HaveOccurred())
 			b := &bytes.Buffer{}
-			f1.Write(b, 2, 0)
-			f2.Write(b, 2, 0)
-			f3.Write(b, 2, 0)
+			f1.Write(b, 0)
+			f2.Write(b, 0)
+			f3.Write(b, 0)
 			Expect(len(p.frames)).To(Equal(3))
 			Expect(p.frames[0].(*frames.StreamFrame).DataLenPresent).To(BeTrue())
 			Expect(p.frames[1].(*frames.StreamFrame).DataLenPresent).To(BeTrue())
diff --git a/packet_unpacker_test.go b/packet_unpacker_test.go
index 30a2c589..b37cb8f6 100644
--- a/packet_unpacker_test.go
+++ b/packet_unpacker_test.go
@@ -50,7 +50,7 @@ var _ = Describe("Packet unpacker", func() {
 			StreamID: 1,
 			Data:     []byte("foobar"),
 		}
-		err := f.Write(buf, 3, 0)
+		err := f.Write(buf, 0)
 		Expect(err).ToNot(HaveOccurred())
 		setReader(buf.Bytes())
 		packet, err := unpacker.Unpack(hdrBin, hdr, r)
@@ -63,7 +63,7 @@ var _ = Describe("Packet unpacker", func() {
 			LargestObserved: 1,
 			DelayTime:       time.Microsecond,
 		}
-		err := f.Write(buf, 3, 32)
+		err := f.Write(buf, 32)
 		Expect(err).ToNot(HaveOccurred())
 		setReader(buf.Bytes())
 		packet, err := unpacker.Unpack(hdrBin, hdr, r)
@@ -99,7 +99,7 @@ var _ = Describe("Packet unpacker", func() {
 
 	It("unpacks CONNECTION_CLOSE frames", func() {
 		f := &frames.ConnectionCloseFrame{ReasonPhrase: "foo"}
-		err := f.Write(buf, 6, 0)
+		err := f.Write(buf, 0)
 		Expect(err).ToNot(HaveOccurred())
 		setReader(buf.Bytes())
 		packet, err := unpacker.Unpack(hdrBin, hdr, r)