diff --git a/merkledag/utils/diffenum.go b/merkledag/utils/diffenum.go
index bc7e09321207..f135281447a8 100644
--- a/merkledag/utils/diffenum.go
+++ b/merkledag/utils/diffenum.go
@@ -55,13 +55,15 @@ func DiffEnumerate(ctx context.Context, dserv node.NodeGetter, from, to *cid.Cid
 	return nil
 }
 
+// if both bef and aft are not nil, then that signifies bef was replaces with aft.
+// if bef is nil and aft is not, that means aft was newly added
+// if aft is nil and bef is not, that means bef was deleted
 type diffpair struct {
 	bef, aft *cid.Cid
 }
 
-// getLinkDiff returns a changset (minimum edit distance style) between nodes
-// 'a' and 'b'. Currently does not log deletions as our usecase doesnt call for
-// this.
+// getLinkDiff returns a changeset between nodes 'a' and 'b'. Currently does
+// not log deletions as our usecase doesnt call for this.
 func getLinkDiff(a, b node.Node) []diffpair {
 	have := make(map[string]*node.Link)
 	names := make(map[string]*node.Link)
diff --git a/pin/pin.go b/pin/pin.go
index 8de1780f09cb..482d070fd50f 100644
--- a/pin/pin.go
+++ b/pin/pin.go
@@ -90,7 +90,7 @@ type Pinner interface {
 	// Update updates a recursive pin from one cid to another
 	// this is more efficient than simply pinning the new one and unpinning the
 	// old one
-	Update(context.Context, *cid.Cid, *cid.Cid, bool) error
+	Update(ctx context.Context, from, to *cid.Cid, unpin bool) error
 
 	// Check if a set of keys are pinned, more efficient than
 	// calling IsPinned for each key