diff --git a/extern/storage-sealing/checks.go b/extern/storage-sealing/checks.go
index af62b9548..b415c6f8e 100644
--- a/extern/storage-sealing/checks.go
+++ b/extern/storage-sealing/checks.go
@@ -79,7 +79,7 @@ func checkPrecommit(ctx context.Context, maddr address.Address, si SectorInfo, t
 		return &ErrApi{xerrors.Errorf("calling StateComputeDataCommitment: %w", err)}
 	}
 
-	if !commD.Equals(*si.CommD) {
+	if si.CommD == nil || !commD.Equals(*si.CommD) {
 		return &ErrBadCommD{xerrors.Errorf("on chain CommD differs from sector: %s != %s", commD, si.CommD)}
 	}
 
diff --git a/extern/storage-sealing/states_sealing.go b/extern/storage-sealing/states_sealing.go
index 1ac22e20f..a434d1fcb 100644
--- a/extern/storage-sealing/states_sealing.go
+++ b/extern/storage-sealing/states_sealing.go
@@ -308,6 +308,10 @@ func (m *Sealing) handleCommitting(ctx statemachine.Context, sector SectorInfo)
 
 	log.Infof("KOMIT %d %x(%d); %x(%d); %v; r:%x; d:%x", sector.SectorNumber, sector.TicketValue, sector.TicketEpoch, sector.SeedValue, sector.SeedEpoch, sector.pieceInfos(), sector.CommR, sector.CommD)
 
+	if sector.CommD == nil || sector.CommR == nil {
+		return ctx.Send(SectorCommitFailed{xerrors.Errorf("sector had nil commR or commD")})
+	}
+
 	cids := storage.SectorCids{
 		Unsealed: *sector.CommD,
 		Sealed:   *sector.CommR,