diff --git a/plumbing/format/commitgraph/commitgraph_test.go b/plumbing/format/commitgraph/commitgraph_test.go
index b98414251..837f32f61 100644
--- a/plumbing/format/commitgraph/commitgraph_test.go
+++ b/plumbing/format/commitgraph/commitgraph_test.go
@@ -116,8 +116,7 @@ func (s *CommitgraphSuite) TestReencodeInMemory(c *C) {
 		for i, hash := range index.Hashes() {
 			node, err := index.GetNodeByIndex(i)
 			c.Assert(err, IsNil)
-			err = memoryIndex.Add(hash, node)
-			c.Assert(err, IsNil)
+			memoryIndex.Add(hash, node)
 		}
 		reader.Close()
 
diff --git a/plumbing/format/commitgraph/file.go b/plumbing/format/commitgraph/file.go
index dce62436c..26dff39ee 100644
--- a/plumbing/format/commitgraph/file.go
+++ b/plumbing/format/commitgraph/file.go
@@ -14,11 +14,11 @@ import (
 var (
 	// ErrUnsupportedVersion is returned by OpenFileIndex when the commit graph
 	// file version is not supported.
-	ErrUnsupportedVersion = errors.New("Unsuported version")
+	ErrUnsupportedVersion = errors.New("Unsupported version")
 	// ErrUnsupportedHash is returned by OpenFileIndex when the commit graph
 	// hash function is not supported. Currently only SHA-1 is defined and
 	// supported
-	ErrUnsupportedHash = errors.New("Unsuported hash algorithm")
+	ErrUnsupportedHash = errors.New("Unsupported hash algorithm")
 	// ErrMalformedCommitGraphFile is returned by OpenFileIndex when the commit
 	// graph file is corrupted.
 	ErrMalformedCommitGraphFile = errors.New("Malformed commit graph file")
diff --git a/plumbing/format/commitgraph/memory.go b/plumbing/format/commitgraph/memory.go
index 316bc6d57..1d57a07e3 100644
--- a/plumbing/format/commitgraph/memory.go
+++ b/plumbing/format/commitgraph/memory.go
@@ -60,12 +60,11 @@ func (mi *MemoryIndex) Hashes() []plumbing.Hash {
 }
 
 // Add adds new node to the memory index
-func (mi *MemoryIndex) Add(hash plumbing.Hash, node *Node) error {
+func (mi *MemoryIndex) Add(hash plumbing.Hash, node *Node) {
 	// The parent indexes are calculated lazily in GetNodeByIndex
 	// which allows adding nodes out of order as long as all parents
 	// are eventually resolved
 	node.ParentIndexes = nil
 	mi.indexMap[hash] = len(mi.commitData)
 	mi.commitData = append(mi.commitData, node)
-	return nil
 }