diff --git a/lib/statestore/store.go b/lib/statestore/store.go
index c32c3ff22..994938223 100644
--- a/lib/statestore/store.go
+++ b/lib/statestore/store.go
@@ -39,7 +39,7 @@ func (st *StateStore) Begin(i interface{}, state interface{}) error {
 		return err
 	}
 	if has {
-		return xerrors.Errorf("Already tracking state for %s", i)
+		return xerrors.Errorf("already tracking state for %v", i)
 	}
 
 	b, err := cborutil.Dump(state)
@@ -111,12 +111,16 @@ func (st *StateStore) mutate(i interface{}, mutator func([]byte) ([]byte, error)
 	return st.ds.Put(k, mutated)
 }
 
+func (st *StateStore) Has(i interface{}) (bool, error) {
+	return st.ds.Has(toKey(i))
+}
+
 func (st *StateStore) Get(i interface{}, out cbg.CBORUnmarshaler) error {
 	k := toKey(i)
 	val, err := st.ds.Get(k)
 	if err != nil {
 		if xerrors.Is(err, datastore.ErrNotFound) {
-			return xerrors.Errorf("No state for %s", i)
+			return xerrors.Errorf("No state for %s: %w", i, err)
 		}
 		return err
 	}
diff --git a/storage/sealing.go b/storage/sealing.go
index 637eb8da2..a2723680d 100644
--- a/storage/sealing.go
+++ b/storage/sealing.go
@@ -61,6 +61,15 @@ func (m *Miner) sectorStateLoop(ctx context.Context) {
 }
 
 func (m *Miner) onSectorIncoming(sector *SectorInfo) {
+	has, err := m.sectors.Has(sector.SectorID)
+	if err != nil {
+		return
+	}
+	if has {
+		log.Warnf("SealSector called more than once for sector %d", sector.SectorID)
+		return
+	}
+
 	if err := m.sectors.Begin(sector.SectorID, sector); err != nil {
 		// We may have re-sent the proposal
 		log.Errorf("deal tracking failed: %s", err)