diff --git a/public_header.go b/public_header.go
index 6c120f64..f55a0507 100644
--- a/public_header.go
+++ b/public_header.go
@@ -35,7 +35,7 @@ func (h *PublicHeader) WritePublicHeader(b *bytes.Buffer) error {
 
 	b.WriteByte(publicFlagByte)
 	utils.WriteUint64(b, uint64(h.ConnectionID)) // TODO: Send shorter connection id if possible
-	utils.WriteUint32(b, uint32(h.PacketNumber)) // TODO: Send shorter packet number if possible
+	utils.WriteUint48(b, uint64(h.PacketNumber)) // TODO: Send shorter packet number if possible
 	return nil
 }
 
diff --git a/public_header_test.go b/public_header_test.go
index 15fde1de..48ca81e3 100644
--- a/public_header_test.go
+++ b/public_header_test.go
@@ -79,7 +79,7 @@ var _ = Describe("Public Header", func() {
 				PacketNumber: 2,
 			}
 			publicHeader.WritePublicHeader(b)
-			Expect(b.Bytes()).To(Equal([]byte{0x2c, 0xf6, 0x19, 0x86, 0x66, 0x9b, 0x9f, 0xfa, 0x4c, 2, 0, 0, 0}))
+			Expect(b.Bytes()).To(Equal([]byte{0x2c, 0xf6, 0x19, 0x86, 0x66, 0x9b, 0x9f, 0xfa, 0x4c, 2, 0, 0, 0, 0, 0}))
 		})
 
 		It("sets the Version Flag", func() {