diff --git a/session_test.go b/session_test.go
index 7f9b61d2..677cf580 100644
--- a/session_test.go
+++ b/session_test.go
@@ -1004,12 +1004,10 @@ var _ = Describe("Session", func() {
 	})
 
 	Context("sending packets", func() {
+		var sessionDone chan struct{}
+
 		BeforeEach(func() {
-			cryptoSetup.EXPECT().RunHandshake().MaxTimes(1)
-			go func() {
-				defer GinkgoRecover()
-				sess.run()
-			}()
+			sessionDone = make(chan struct{})
 		})
 
 		AfterEach(func() {
@@ -1021,27 +1019,38 @@ var _ = Describe("Session", func() {
 			qlogger.EXPECT().Export()
 			sess.shutdown()
 			Eventually(sess.Context().Done()).Should(BeClosed())
+			Eventually(sessionDone).Should(BeClosed())
 		})
 
+		runSession := func() {
+			go func() {
+				defer GinkgoRecover()
+				cryptoSetup.EXPECT().RunHandshake().MaxTimes(1)
+				sess.run()
+				close(sessionDone)
+			}()
+		}
+
 		It("sends packets", func() {
 			sess.handshakeConfirmed = true
+			runSession()
 			p := getPacket(1)
 			packer.EXPECT().PackPacket().Return(p, nil)
-			sess.receivedPacketHandler.ReceivedPacket(0x035e, protocol.Encryption1RTT, time.Now(), true)
-			mconn.EXPECT().Write(gomock.Any())
+			packer.EXPECT().PackPacket().Return(nil, nil)
+			sent := make(chan struct{})
+			mconn.EXPECT().Write(gomock.Any()).Do(func([]byte) { close(sent) })
 			qlogger.EXPECT().SentPacket(p.header, p.buffer.Len(), nil, []wire.Frame{})
-			sent, err := sess.sendPacket()
-			Expect(err).NotTo(HaveOccurred())
-			Expect(sent).To(BeTrue())
+			sess.scheduleSending()
+			Eventually(sent).Should(BeClosed())
 		})
 
 		It("doesn't send packets if there's nothing to send", func() {
 			sess.handshakeConfirmed = true
+			runSession()
 			packer.EXPECT().PackPacket().Return(nil, nil)
 			sess.receivedPacketHandler.ReceivedPacket(0x035e, protocol.Encryption1RTT, time.Now(), true)
-			sent, err := sess.sendPacket()
-			Expect(err).NotTo(HaveOccurred())
-			Expect(sent).To(BeFalse())
+			sess.scheduleSending()
+			time.Sleep(50 * time.Millisecond) // make sure there are no calls to mconn.Write()
 		})
 
 		It("sends ACK only packets", func() {
@@ -1050,6 +1059,7 @@ var _ = Describe("Session", func() {
 			sph.EXPECT().SendMode().Return(ackhandler.SendAck)
 			sph.EXPECT().ShouldSendNumPackets().Return(1000)
 			packer.EXPECT().MaybePackAckPacket(false)
+			runSession()
 			sess.sentPacketHandler = sph
 			Expect(sess.sendPackets()).To(Succeed())
 		})
@@ -1058,14 +1068,17 @@ var _ = Describe("Session", func() {
 			sess.handshakeConfirmed = true
 			fc := mocks.NewMockConnectionFlowController(mockCtrl)
 			fc.EXPECT().IsNewlyBlocked().Return(true, protocol.ByteCount(1337))
+			fc.EXPECT().IsNewlyBlocked()
 			p := getPacket(1)
 			packer.EXPECT().PackPacket().Return(p, nil)
+			packer.EXPECT().PackPacket().Return(nil, nil)
 			sess.connFlowController = fc
-			mconn.EXPECT().Write(gomock.Any())
+			runSession()
+			sent := make(chan struct{})
+			mconn.EXPECT().Write(gomock.Any()).Do(func([]byte) { close(sent) })
 			qlogger.EXPECT().SentPacket(p.header, p.length, nil, []wire.Frame{})
-			sent, err := sess.sendPacket()
-			Expect(err).NotTo(HaveOccurred())
-			Expect(sent).To(BeTrue())
+			sess.scheduleSending()
+			Eventually(sent).Should(BeClosed())
 			frames, _ := sess.framer.AppendControlFrames(nil, 1000)
 			Expect(frames).To(Equal([]ackhandler.Frame{{Frame: &wire.DataBlockedFrame{DataLimit: 1337}}}))
 		})
@@ -1074,8 +1087,11 @@ var _ = Describe("Session", func() {
 			sph := mockackhandler.NewMockSentPacketHandler(mockCtrl)
 			sph.EXPECT().GetLossDetectionTimeout().AnyTimes()
 			sph.EXPECT().SendMode().Return(ackhandler.SendNone)
+			sph.EXPECT().TimeUntilSend().AnyTimes()
 			sess.sentPacketHandler = sph
-			Expect(sess.sendPackets()).To(Succeed())
+			runSession()
+			sess.scheduleSending()
+			time.Sleep(50 * time.Millisecond)
 		})
 
 		for _, enc := range []protocol.EncryptionLevel{protocol.EncryptionInitial, protocol.EncryptionHandshake, protocol.Encryption1RTT} {
@@ -1102,7 +1118,7 @@ var _ = Describe("Session", func() {
 				It("sends a probe packet", func() {
 					sph := mockackhandler.NewMockSentPacketHandler(mockCtrl)
 					sph.EXPECT().GetLossDetectionTimeout().AnyTimes()
-					sph.EXPECT().TimeUntilSend()
+					sph.EXPECT().TimeUntilSend().AnyTimes()
 					sph.EXPECT().SendMode().Return(sendMode)
 					sph.EXPECT().ShouldSendNumPackets().Return(1)
 					sph.EXPECT().QueueProbePacket(encLevel)
@@ -1112,15 +1128,18 @@ var _ = Describe("Session", func() {
 						Expect(packet.PacketNumber).To(Equal(protocol.PacketNumber(123)))
 					})
 					sess.sentPacketHandler = sph
-					mconn.EXPECT().Write(gomock.Any())
+					runSession()
+					sent := make(chan struct{})
+					mconn.EXPECT().Write(gomock.Any()).Do(func([]byte) { close(sent) })
 					qlogger.EXPECT().SentPacket(p.header, p.length, gomock.Any(), gomock.Any())
-					Expect(sess.sendPackets()).To(Succeed())
+					sess.scheduleSending()
+					Eventually(sent).Should(BeClosed())
 				})
 
 				It("sends a PING as a probe packet", func() {
 					sph := mockackhandler.NewMockSentPacketHandler(mockCtrl)
 					sph.EXPECT().GetLossDetectionTimeout().AnyTimes()
-					sph.EXPECT().TimeUntilSend()
+					sph.EXPECT().TimeUntilSend().AnyTimes()
 					sph.EXPECT().SendMode().Return(sendMode)
 					sph.EXPECT().ShouldSendNumPackets().Return(1)
 					sph.EXPECT().QueueProbePacket(encLevel).Return(false)
@@ -1130,9 +1149,12 @@ var _ = Describe("Session", func() {
 						Expect(packet.PacketNumber).To(Equal(protocol.PacketNumber(123)))
 					})
 					sess.sentPacketHandler = sph
-					mconn.EXPECT().Write(gomock.Any())
+					runSession()
+					sent := make(chan struct{})
+					mconn.EXPECT().Write(gomock.Any()).Do(func([]byte) { close(sent) })
 					qlogger.EXPECT().SentPacket(p.header, p.length, gomock.Any(), gomock.Any())
-					Expect(sess.sendPackets()).To(Succeed())
+					sess.scheduleSending()
+					Eventually(sent).Should(BeClosed())
 					// We're using a mock packet packer in this test.
 					// We therefore need to test separately that the PING was actually queued.
 					Expect(getFrame(1000)).To(BeAssignableToTypeOf(&wire.PingFrame{}))