diff --git a/chain/stmgr/utils.go b/chain/stmgr/utils.go
index e6ba47665..ce9326e0a 100644
--- a/chain/stmgr/utils.go
+++ b/chain/stmgr/utils.go
@@ -426,7 +426,7 @@ func GetLookbackTipSetForRound(ctx context.Context, sm *StateManager, ts *types.
 		return ts, nil
 	}
 
-	lbts, err := sm.ChainStore().GetTipsetByHeight(ctx, lbr, ts)
+	lbts, err := sm.ChainStore().GetTipsetByHeight(ctx, lbr, ts, true)
 	if err != nil {
 		return nil, xerrors.Errorf("failed to get lookback tipset: %w", err)
 	}
diff --git a/chain/store/store.go b/chain/store/store.go
index cde8add51..3985372c6 100644
--- a/chain/store/store.go
+++ b/chain/store/store.go
@@ -930,7 +930,11 @@ func (cs *ChainStore) GetRandomness(ctx context.Context, blks []cid.Cid, pers cr
 	}
 }
 
-func (cs *ChainStore) GetTipsetByHeight(ctx context.Context, h abi.ChainEpoch, ts *types.TipSet) (*types.TipSet, error) {
+// GetTipsetByHeight returns the tipset on the chain behind 'ts' at the given
+// height. In the case that the given height is a null round, the 'prev' flag
+// selects the tipset before the null round if true, and the tipset following
+// the null round if false.
+func (cs *ChainStore) GetTipsetByHeight(ctx context.Context, h abi.ChainEpoch, ts *types.TipSet, prev bool) (*types.TipSet, error) {
 	if ts == nil {
 		ts = cs.GetHeaviestTipSet()
 	}
@@ -954,6 +958,9 @@ func (cs *ChainStore) GetTipsetByHeight(ctx context.Context, h abi.ChainEpoch, t
 		}
 
 		if h > pts.Height() {
+			if prev {
+				return pts, nil
+			}
 			return ts, nil
 		}
 		if h == pts.Height() {
diff --git a/cmd/lotus-bench/import.go b/cmd/lotus-bench/import.go
index 8911856c3..c7062fba5 100644
--- a/cmd/lotus-bench/import.go
+++ b/cmd/lotus-bench/import.go
@@ -85,7 +85,7 @@ var importBenchCmd = &cli.Command{
 		}
 
 		if h := cctx.Int64("height"); h != 0 {
-			tsh, err := cs.GetTipsetByHeight(context.TODO(), abi.ChainEpoch(h), head)
+			tsh, err := cs.GetTipsetByHeight(context.TODO(), abi.ChainEpoch(h), head, true)
 			if err != nil {
 				return err
 			}
diff --git a/node/impl/full/chain.go b/node/impl/full/chain.go
index 076968987..8b00cfb34 100644
--- a/node/impl/full/chain.go
+++ b/node/impl/full/chain.go
@@ -174,7 +174,7 @@ func (a *ChainAPI) ChainGetTipSetByHeight(ctx context.Context, h abi.ChainEpoch,
 	if err != nil {
 		return nil, xerrors.Errorf("loading tipset %s: %w", tsk, err)
 	}
-	return a.Chain.GetTipsetByHeight(ctx, h, ts)
+	return a.Chain.GetTipsetByHeight(ctx, h, ts, true)
 }
 
 func (a *ChainAPI) ChainReadObj(ctx context.Context, obj cid.Cid) ([]byte, error) {