diff --git a/blockservice/blockservice.go b/blockservice/blockservice.go
index c6ecbc386..d746f2fe0 100644
--- a/blockservice/blockservice.go
+++ b/blockservice/blockservice.go
@@ -32,7 +32,6 @@ type BlockService interface {
 	GetBlock(ctx context.Context, c *cid.Cid) (blocks.Block, error)
 	GetBlocks(ctx context.Context, ks []*cid.Cid) <-chan blocks.Block
 	DeleteBlock(o blocks.Block) error
-	NewSession(context.Context) *Session
 	Close() error
 }
 
@@ -79,18 +78,18 @@ func (bs *blockService) Exchange() exchange.Interface {
 	return bs.exchange
 }
 
-func (bs *blockService) NewSession(ctx context.Context) *Session {
-	bswap, ok := bs.Exchange().(*bitswap.Bitswap)
-	if ok {
+func NewSession(ctx context.Context, bs BlockService) *Session {
+	exchange := bs.Exchange()
+	if bswap, ok := exchange.(*bitswap.Bitswap); ok {
 		ses := bswap.NewSession(ctx)
 		return &Session{
 			ses: ses,
-			bs:  bs.blockstore,
+			bs:  bs.Blockstore(),
 		}
 	}
 	return &Session{
-		ses: bs.exchange,
-		bs:  bs.blockstore,
+		ses: exchange,
+		bs:  bs.Blockstore(),
 	}
 }
 
diff --git a/merkledag/merkledag.go b/merkledag/merkledag.go
index 9fa8446d8..587c481cb 100644
--- a/merkledag/merkledag.go
+++ b/merkledag/merkledag.go
@@ -182,7 +182,7 @@ func FetchGraph(ctx context.Context, root *cid.Cid, serv DAGService) error {
 	var ng node.NodeGetter = serv
 	ds, ok := serv.(*dagService)
 	if ok {
-		ng = &sesGetter{ds.Blocks.NewSession(ctx)}
+		ng = &sesGetter{bserv.NewSession(ctx, ds.Blocks)}
 	}
 
 	v, _ := ctx.Value("progress").(*ProgressTracker)