diff --git a/backend/app/cmd/avatar.go b/backend/app/cmd/avatar.go
index 7321a09f..52174fe5 100644
--- a/backend/app/cmd/avatar.go
+++ b/backend/app/cmd/avatar.go
@@ -13,7 +13,8 @@ import (
 )
 
 // AvatarCommand set of flags and command for avatar migration
-// it converts all avatarts from src.type to dst.type
+// it converts all avatars from src.type to dst.type.
+// Note: it is possible to run migration for the same types (src = dst) in order to resize all avatars.
 type AvatarCommand struct {
 	AvatarSrc AvatarGroup `group:"src" namespace:"src"`
 	AvatarDst AvatarGroup `group:"dst" namespace:"dst"`
diff --git a/backend/app/store/avatar/bolt.go b/backend/app/store/avatar/bolt.go
index 90ed197f..826a1ded 100644
--- a/backend/app/store/avatar/bolt.go
+++ b/backend/app/store/avatar/bolt.go
@@ -15,8 +15,8 @@ import (
 )
 
 // BoltDB implements avatar store with bolt
-// using separate db (file) with "avatars" bucket to keep image bin and "metas" bucket to keep sha1
-// avatarID (base file name) used as a key
+// using separate db (file) with "avatars" bucket to keep image bin and "metas" bucket
+// to keep sha1 of picture. avatarID (base file name) used as a key for both.
 type BoltDB struct {
 	fileName    string // full path to boltdb
 	resizeLimit int
@@ -45,7 +45,7 @@ func NewBoltDB(fileName string, options bolt.Options, resizeLimit int) (*BoltDB,
 	return &BoltDB{db: db, fileName: fileName, resizeLimit: resizeLimit}, nil
 }
 
-// Put avatar to bolt, key by avatarID
+// Put avatar to bolt, key by avatarID. Trying to resize image and lso calculates sha1 of the file for ID func
 func (b *BoltDB) Put(userID string, reader io.Reader) (avatar string, err error) {
 	id := encodeID(userID)
 
@@ -64,7 +64,8 @@ func (b *BoltDB) Put(userID string, reader io.Reader) (avatar string, err error)
 		if err = tx.Bucket([]byte(avatarsBktName)).Put([]byte(avatarID), buf.Bytes()); err != nil {
 			return errors.Wrapf(err, "can't put to bucket with %s", avatarID)
 		}
-		return tx.Bucket([]byte(metasBktName)).Put([]byte(avatarID), []byte(b.sha1(buf.Bytes(), id)))
+		// store sha1 of the image
+		return tx.Bucket([]byte(metasBktName)).Put([]byte(avatarID), []byte(b.sha1(buf.Bytes(), avatarID)))
 	})
 	return avatarID, err
 }
@@ -87,16 +88,17 @@ func (b *BoltDB) Get(avatarID string) (reader io.ReadCloser, size int, err error
 func (b *BoltDB) ID(avatarID string) (id string) {
 	data := []byte{}
 	err := b.db.View(func(tx *bolt.Tx) error {
-		data = tx.Bucket([]byte(metasBktName)).Get([]byte(avatarID))
-		if data == nil {
+		if data = tx.Bucket([]byte(metasBktName)).Get([]byte(avatarID)); data == nil {
 			return errors.Errorf("can't load avatar's id for %s", avatarID)
 		}
 		return nil
 	})
-	if err != nil {
+
+	if err != nil { // failed to get ID, use encoded avatarID
 		log.Printf("[DEBUG] can't get avatar info '%s', %s", avatarID, err)
 		return store.EncodeID(avatarID)
 	}
+
 	return string(data)
 }
 
diff --git a/backend/app/store/avatar/bolt_test.go b/backend/app/store/avatar/bolt_test.go
index 4db0376e..b9ddac23 100644
--- a/backend/app/store/avatar/bolt_test.go
+++ b/backend/app/store/avatar/bolt_test.go
@@ -35,8 +35,9 @@ func TestBoltDB_PutAndGet(t *testing.T) {
 	_, _, err = b.Get("bad avatar")
 	assert.NotNil(t, err)
 
+	// check IDs
 	assert.Equal(t, "fddae9ce556712a6ece0e8951a6e7a05c51ed6bf", b.ID(avatar))
-	assert.Equal(t, "70c881d4a26984ddce795f6f71817c9cf4480e79", b.ID("aaaa"), "no data, encode avatar id")
+	assert.Equal(t, "70c881d4a26984ddce795f6f71817c9cf4480e79", b.ID("aaaa"), "no data, encoded avatar id")
 
 	l, err := b.List()
 	require.Nil(t, err)
diff --git a/backend/app/store/avatar/store.go b/backend/app/store/avatar/store.go
index a3876207..eb9a3aed 100644
--- a/backend/app/store/avatar/store.go
+++ b/backend/app/store/avatar/store.go
@@ -1,4 +1,5 @@
-// Package avatar defines store interface and implements local (fs) and gridfs (mongo) stores.
+// Package avatar defines store interface and implements local (fs), gridfs (mongo) and boltdb stores.
+//
 package avatar
 
 //go:generate sh -c "mockery -inpkg -name Store -print > /tmp/mock.tmp && mv /tmp/mock.tmp store_mock.go"
@@ -32,7 +33,7 @@ type Store interface {
 	ID(avatarID string) (id string)                                   // unique id of stored avatar's data
 	Remove(avatarID string) error                                     // remove avatar data
 	List() (ids []string, err error)                                  // list all avatar ids
-	Close() error
+	Close() error                                                     // close store
 }
 
 // Migrate avatars between stores