diff --git a/api/test/tape.go b/api/test/tape.go
new file mode 100644
index 0000000000..466bdd829a
--- /dev/null
+++ b/api/test/tape.go
@@ -0,0 +1,114 @@
+package test
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/filecoin-project/go-state-types/abi"
+	"github.com/filecoin-project/go-state-types/network"
+	"github.com/filecoin-project/lotus/api"
+	"github.com/filecoin-project/lotus/build"
+	"github.com/filecoin-project/lotus/chain/stmgr"
+	sealing "github.com/filecoin-project/lotus/extern/storage-sealing"
+	"github.com/filecoin-project/lotus/node"
+	"github.com/filecoin-project/lotus/node/impl"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTapeFix(t *testing.T, b APIBuilder, blocktime time.Duration) {
+	t.Run("before", func(t *testing.T) { testTapeFix(t, b, blocktime, false) })
+	t.Run("after", func(t *testing.T) { testTapeFix(t, b, blocktime, true) })
+}
+func testTapeFix(t *testing.T, b APIBuilder, blocktime time.Duration, after bool) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	upgradeSchedule := stmgr.UpgradeSchedule{{
+		Network:   build.ActorUpgradeNetworkVersion,
+		Height:    1,
+		Migration: stmgr.UpgradeActorsV2,
+	}}
+	if after {
+		upgradeSchedule = append(upgradeSchedule, stmgr.Upgrade{
+			Network: network.Version5,
+			Height:  2,
+		})
+	}
+
+	n, sn := b(t, []FullNodeOpts{{Opts: func(_ []TestNode) node.Option {
+		return node.Override(new(stmgr.UpgradeSchedule), upgradeSchedule)
+	}}}, OneMiner)
+
+	client := n[0].FullNode.(*impl.FullNodeAPI)
+	miner := sn[0]
+
+	addrinfo, err := client.NetAddrsListen(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := miner.NetConnect(ctx, addrinfo); err != nil {
+		t.Fatal(err)
+	}
+	build.Clock.Sleep(time.Second)
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		for ctx.Err() == nil {
+			build.Clock.Sleep(blocktime)
+			if err := sn[0].MineOne(ctx, MineNext); err != nil {
+				if ctx.Err() != nil {
+					// context was canceled, ignore the error.
+					return
+				}
+				t.Error(err)
+			}
+		}
+	}()
+	defer func() {
+		cancel()
+		<-done
+	}()
+
+	err = miner.PledgeSector(ctx)
+	require.NoError(t, err)
+
+	// Wait till done.
+	var sectorNo abi.SectorNumber
+	for {
+		s, err := miner.SectorsList(ctx) // Note - the test builder doesn't import genesis sectors into FSM
+		require.NoError(t, err)
+		fmt.Printf("Sectors: %d\n", len(s))
+		if len(s) == 1 {
+			sectorNo = s[0]
+			break
+		}
+
+		build.Clock.Sleep(100 * time.Millisecond)
+	}
+
+	fmt.Printf("All sectors is fsm\n")
+
+	// If before, we expect the precommit to fail
+	successState := api.SectorState(sealing.CommitFailed)
+	failureState := api.SectorState(sealing.Proving)
+	if after {
+		// otherwise, it should succeed.
+		successState, failureState = failureState, successState
+	}
+
+	for {
+		st, err := miner.SectorsStatus(ctx, sectorNo, false)
+		require.NoError(t, err)
+		if st.State == successState {
+			break
+		}
+		require.NotEqual(t, failureState, st.State)
+		build.Clock.Sleep(100 * time.Millisecond)
+		fmt.Println("WaitSeal")
+	}
+
+}
diff --git a/api/test/test.go b/api/test/test.go
index 35b3977408..947f2bef43 100644
--- a/api/test/test.go
+++ b/api/test/test.go
@@ -12,6 +12,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/filecoin-project/go-state-types/abi"
+	"github.com/filecoin-project/go-state-types/network"
 	"github.com/filecoin-project/lotus/api"
 	"github.com/filecoin-project/lotus/build"
 	"github.com/filecoin-project/lotus/miner"
@@ -96,7 +97,8 @@ var FullNodeWithUpgradeAt = func(upgradeHeight abi.ChainEpoch) FullNodeOpts {
 	return FullNodeOpts{
 		Opts: func(nodes []TestNode) node.Option {
 			return node.Override(new(stmgr.UpgradeSchedule), stmgr.UpgradeSchedule{{
-				Network:   build.ActorUpgradeNetworkVersion,
+				// Skip directly to tape height so precommits work.
+				Network:   network.Version5,
 				Height:    upgradeHeight,
 				Migration: stmgr.UpgradeActorsV2,
 			}})
diff --git a/extern/sector-storage/mock/mock.go b/extern/sector-storage/mock/mock.go
index 64207e66d1..001c7159cb 100644
--- a/extern/sector-storage/mock/mock.go
+++ b/extern/sector-storage/mock/mock.go
@@ -230,8 +230,8 @@ func (mgr *SectorMgr) SealCommit1(ctx context.Context, sid abi.SectorID, ticket
 }
 
 func (mgr *SectorMgr) SealCommit2(ctx context.Context, sid abi.SectorID, phase1Out storage.Commit1Out) (proof storage.Proof, err error) {
-	var out [32]byte
-	for i := range out {
+	var out [1920]byte
+	for i := range out[:len(phase1Out)] {
 		out[i] = phase1Out[i] ^ byte(sid.Number&0xff)
 	}
 
@@ -407,11 +407,12 @@ func (mgr *SectorMgr) CheckProvable(ctx context.Context, spt abi.RegisteredSealP
 }
 
 func (m mockVerif) VerifySeal(svi proof.SealVerifyInfo) (bool, error) {
-	if len(svi.Proof) != 32 { // Real ones are longer, but this should be fine
+	if len(svi.Proof) != 1920 {
 		return false, nil
 	}
 
-	for i, b := range svi.Proof {
+	// only the first 32 bytes, the rest are 0.
+	for i, b := range svi.Proof[:32] {
 		if b != svi.UnsealedCID.Bytes()[i]+svi.SealedCID.Bytes()[31-i]-svi.InteractiveRandomness[i]*svi.Randomness[i] {
 			return false, nil
 		}
diff --git a/node/node_test.go b/node/node_test.go
index 001b99c04d..e553e83b2f 100644
--- a/node/node_test.go
+++ b/node/node_test.go
@@ -117,6 +117,16 @@ func TestPledgeSectors(t *testing.T) {
 	})
 }
 
+func TestTapeFix(t *testing.T) {
+	logging.SetLogLevel("miner", "ERROR")
+	logging.SetLogLevel("chainstore", "ERROR")
+	logging.SetLogLevel("chain", "ERROR")
+	logging.SetLogLevel("sub", "ERROR")
+	logging.SetLogLevel("storageminer", "ERROR")
+
+	test.TestTapeFix(t, builder.MockSbBuilder, 2*time.Millisecond)
+}
+
 func TestWindowedPost(t *testing.T) {
 	if os.Getenv("LOTUS_TEST_WINDOW_POST") != "1" {
 		t.Skip("this takes a few minutes, set LOTUS_TEST_WINDOW_POST=1 to run")