diff --git a/pkg/object/attribute.go b/pkg/object/attribute.go
index 6af3d21..dbedf69 100644
--- a/pkg/object/attribute.go
+++ b/pkg/object/attribute.go
@@ -48,30 +48,30 @@ func (a *Attribute) ToV2() *object.Attribute {
 //
 // Buffer is allocated when the argument is empty.
 // Otherwise, the first buffer is used.
-func (d *Attribute) Marshal(b ...[]byte) ([]byte, error) {
+func (a *Attribute) Marshal(b ...[]byte) ([]byte, error) {
 	var buf []byte
 	if len(b) > 0 {
 		buf = b[0]
 	}
 
-	return (*object.Attribute)(d).
+	return (*object.Attribute)(a).
 		StableMarshal(buf)
 }
 
 // Unmarshal unmarshals protobuf binary representation of Attribute.
-func (d *Attribute) Unmarshal(data []byte) error {
-	return (*object.Attribute)(d).
+func (a *Attribute) Unmarshal(data []byte) error {
+	return (*object.Attribute)(a).
 		Unmarshal(data)
 }
 
 // MarshalJSON encodes Attribute to protobuf JSON format.
-func (d *Attribute) MarshalJSON() ([]byte, error) {
-	return (*object.Attribute)(d).
+func (a *Attribute) MarshalJSON() ([]byte, error) {
+	return (*object.Attribute)(a).
 		MarshalJSON()
 }
 
 // UnmarshalJSON decodes Attribute from protobuf JSON format.
-func (d *Attribute) UnmarshalJSON(data []byte) error {
-	return (*object.Attribute)(d).
+func (a *Attribute) UnmarshalJSON(data []byte) error {
+	return (*object.Attribute)(a).
 		UnmarshalJSON(data)
 }