diff --git a/extern/storage-sealing/states_sealing.go b/extern/storage-sealing/states_sealing.go
index 5334fc72e..0935823eb 100644
--- a/extern/storage-sealing/states_sealing.go
+++ b/extern/storage-sealing/states_sealing.go
@@ -304,8 +304,6 @@ func (m *Sealing) preCommitParams(ctx statemachine.Context, sector SectorInfo) (
 		return nil, big.Zero(), nil, ctx.Send(SectorSealPreCommit1Failed{xerrors.Errorf("handlePreCommitting: failed to compute pre-commit expiry: %w", err)})
 	}
 
-	// Sectors must last _at least_ MinSectorExpiration + MaxSealDuration.
-	// TODO: The "+10" allows the pre-commit to take 10 blocks to be accepted.
 	nv, err := m.api.StateNetworkVersion(ctx.Context(), tok)
 	if err != nil {
 		return nil, big.Zero(), nil, ctx.Send(SectorSealPreCommit1Failed{xerrors.Errorf("failed to get network version: %w", err)})
@@ -316,7 +314,12 @@ func (m *Sealing) preCommitParams(ctx statemachine.Context, sector SectorInfo) (
 	if minExpiration := sector.TicketEpoch + policy.MaxPreCommitRandomnessLookback + msd + miner.MinSectorExpiration; expiration < minExpiration {
 		expiration = minExpiration
 	}
-	// TODO: enforce a reasonable _maximum_ sector lifetime?
+
+	// Assume: both precommit msg & commit msg land on chain as early as possible
+	maxExpiration := height + policy.GetPreCommitChallengeDelay() + policy.GetMaxSectorExpirationExtension()
+	if expiration > maxExpiration {
+		expiration = maxExpiration
+	}
 
 	params := &miner.SectorPreCommitInfo{
 		Expiration:   expiration,