diff --git a/CHANGELOG.md b/CHANGELOG.md
index c42ccdd..3513989 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## [2.9.1] - 2021-08-26
+
+### Changed
+- String presentation of object type enum.
+
 ## [2.9.0] - 2021-08-16 - Anmyeondo (안면도, 安眠島)
 
 Support "common prefix" attribute match operation to simplify filesystem
@@ -393,3 +398,4 @@ Bump major release
 [2.7.0]: https://github.com/nspcc-dev/neofs-api/compare/v2.6.0...v2.7.0
 [2.8.0]: https://github.com/nspcc-dev/neofs-api/compare/v2.7.0...v2.8.0
 [2.9.0]: https://github.com/nspcc-dev/neofs-api/compare/v2.8.0...v2.9.0
+[2.9.1]: https://github.com/nspcc-dev/neofs-api/compare/v2.9.0...v2.9.1
diff --git a/proto-docs/object.md b/proto-docs/object.md
index c488901..2226eb8 100644
--- a/proto-docs/object.md
+++ b/proto-docs/object.md
@@ -801,14 +801,13 @@ Type of match expression
 
 ### ObjectType
 Type of the object payload content. Only `REGULAR` type objects can be split,
-hence `TOMBSTONE` and `STORAGEGROUP` payload is limited by maximal object
+hence `TOMBSTONE` and `STORAGE_GROUP` payload is limited by maximal object
 size.
 
-String presentation of object type is PascalCased `ObjectType` enumeration
-item name:
-* Regular
-* Tombstone
-* StorageGroup
+String presentation of object type is the same as definition:
+* REGULAR
+* TOMBSTONE
+* STORAGE_GROUP
 
 | Name | Number | Description |
 | ---- | ------ | ----------- |