diff --git a/lib/trie/hash.go b/lib/trie/hash.go
index f798f594b8..887ed83731 100644
--- a/lib/trie/hash.go
+++ b/lib/trie/hash.go
@@ -98,6 +98,8 @@ func encodeNode(n node, buffer *bytes.Buffer, parallel bool) (err error) {
 		n.encodingMu.Lock()
 		defer n.encodingMu.Unlock()
 
+		// TODO remove this copying since it defeats the purpose of `buffer`
+		// and the sync.Pool.
 		n.encoding = make([]byte, buffer.Len())
 		copy(n.encoding, buffer.Bytes())
 		return nil
diff --git a/lib/trie/node.go b/lib/trie/node.go
index b7ae35d9db..cc55da89c3 100644
--- a/lib/trie/node.go
+++ b/lib/trie/node.go
@@ -277,6 +277,8 @@ func (l *leaf) encodeAndHash() (encoding, hash []byte, err error) {
 	bufferBytes := buffer.Bytes()
 
 	l.encodingMu.Lock()
+	// TODO remove this copying since it defeats the purpose of `buffer`
+	// and the sync.Pool.
 	l.encoding = make([]byte, len(bufferBytes))
 	copy(l.encoding, bufferBytes)
 	l.encodingMu.Unlock()