diff --git a/server/ctrlsubsonic/handlers_by_tags.go b/server/ctrlsubsonic/handlers_by_tags.go
index e0c2343..bbae6fa 100644
--- a/server/ctrlsubsonic/handlers_by_tags.go
+++ b/server/ctrlsubsonic/handlers_by_tags.go
@@ -265,7 +265,7 @@ func (c *Controller) ServeGetArtistInfoTwo(r *http.Request) *spec.Response {
 			continue
 		}
 		similar := &spec.SimilarArtist{
-			ID: specid.ID{Type: specid.Artist, Value: -1},
+			ID: &specid.ID{Type: specid.Artist, Value: -1},
 		}
 		if artist.ID != 0 {
 			similar.ID = artist.SID()
diff --git a/server/ctrlsubsonic/spec/spec.go b/server/ctrlsubsonic/spec/spec.go
index eb23f49..50e0fb8 100644
--- a/server/ctrlsubsonic/spec/spec.go
+++ b/server/ctrlsubsonic/spec/spec.go
@@ -91,15 +91,15 @@ type Albums struct {
 
 type Album struct {
 	// common
-	ID       specid.ID `xml:"id,attr,omitempty"       json:"id"`
-	CoverID  specid.ID `xml:"coverArt,attr,omitempty" json:"coverArt,omitempty"`
-	ArtistID specid.ID `xml:"artistId,attr,omitempty" json:"artistId,omitempty"`
-	Artist   string    `xml:"artist,attr,omitempty"   json:"artist,omitempty"`
+	ID       *specid.ID `xml:"id,attr,omitempty"       json:"id"`
+	CoverID  *specid.ID `xml:"coverArt,attr,omitempty" json:"coverArt,omitempty"`
+	ArtistID *specid.ID `xml:"artistId,attr,omitempty" json:"artistId,omitempty"`
+	Artist   string     `xml:"artist,attr,omitempty"   json:"artist,omitempty"`
 	// browsing by folder (eg. getAlbumList)
-	Title    string    `xml:"title,attr"            json:"title"`
-	Album    string    `xml:"album,attr"            json:"album"`
-	ParentID specid.ID `xml:"parent,attr,omitempty" json:"parent,omitempty"`
-	IsDir    bool      `xml:"isDir,attr,omitempty"  json:"isDir,omitempty"`
+	Title    string     `xml:"title,attr"            json:"title"`
+	Album    string     `xml:"album,attr"            json:"album"`
+	ParentID *specid.ID `xml:"parent,attr,omitempty" json:"parent,omitempty"`
+	IsDir    bool       `xml:"isDir,attr,omitempty"  json:"isDir,omitempty"`
 	// browsing by tags (eg. getAlbumList2)
 	Name       string        `xml:"name,attr"              json:"name"`
 	TrackCount int           `xml:"songCount,attr"         json:"songCount"`
@@ -119,27 +119,27 @@ type TracksByGenre struct {
 }
 
 type TrackChild struct {
-	Album       string    `xml:"album,attr,omitempty"       json:"album,omitempty"`
-	AlbumID     specid.ID `xml:"albumId,attr,omitempty"     json:"albumId,omitempty"`
-	Artist      string    `xml:"artist,attr,omitempty"      json:"artist,omitempty"`
-	ArtistID    specid.ID `xml:"artistId,attr,omitempty"    json:"artistId,omitempty"`
-	Bitrate     int       `xml:"bitRate,attr,omitempty"     json:"bitRate,omitempty"`
-	ContentType string    `xml:"contentType,attr,omitempty" json:"contentType,omitempty"`
-	CoverID     specid.ID `xml:"coverArt,attr,omitempty"    json:"coverArt,omitempty"`
-	CreatedAt   time.Time `xml:"created,attr,omitempty"     json:"created,omitempty"`
-	Duration    int       `xml:"duration,attr,omitempty"    json:"duration,omitempty"`
-	Genre       string    `xml:"genre,attr,omitempty"       json:"genre,omitempty"`
-	ID          specid.ID `xml:"id,attr,omitempty"          json:"id,omitempty"`
-	IsDir       bool      `xml:"isDir,attr"                 json:"isDir"`
-	IsVideo     bool      `xml:"isVideo,attr"               json:"isVideo"`
-	ParentID    specid.ID `xml:"parent,attr,omitempty"      json:"parent,omitempty"`
-	Path        string    `xml:"path,attr,omitempty"        json:"path,omitempty"`
-	Size        int       `xml:"size,attr,omitempty"        json:"size,omitempty"`
-	Suffix      string    `xml:"suffix,attr,omitempty"      json:"suffix,omitempty"`
-	Title       string    `xml:"title,attr"                 json:"title"`
-	TrackNumber int       `xml:"track,attr,omitempty"       json:"track,omitempty"`
-	DiscNumber  int       `xml:"discNumber,attr,omitempty"  json:"discNumber,omitempty"`
-	Type        string    `xml:"type,attr,omitempty"        json:"type,omitempty"`
+	Album       string     `xml:"album,attr,omitempty"       json:"album,omitempty"`
+	AlbumID     *specid.ID `xml:"albumId,attr,omitempty"     json:"albumId,omitempty"`
+	Artist      string     `xml:"artist,attr,omitempty"      json:"artist,omitempty"`
+	ArtistID    *specid.ID `xml:"artistId,attr,omitempty"    json:"artistId,omitempty"`
+	Bitrate     int        `xml:"bitRate,attr,omitempty"     json:"bitRate,omitempty"`
+	ContentType string     `xml:"contentType,attr,omitempty" json:"contentType,omitempty"`
+	CoverID     *specid.ID `xml:"coverArt,attr,omitempty"    json:"coverArt,omitempty"`
+	CreatedAt   time.Time  `xml:"created,attr,omitempty"     json:"created,omitempty"`
+	Duration    int        `xml:"duration,attr,omitempty"    json:"duration,omitempty"`
+	Genre       string     `xml:"genre,attr,omitempty"       json:"genre,omitempty"`
+	ID          *specid.ID `xml:"id,attr,omitempty"          json:"id,omitempty"`
+	IsDir       bool       `xml:"isDir,attr"                 json:"isDir"`
+	IsVideo     bool       `xml:"isVideo,attr"               json:"isVideo"`
+	ParentID    *specid.ID `xml:"parent,attr,omitempty"      json:"parent,omitempty"`
+	Path        string     `xml:"path,attr,omitempty"        json:"path,omitempty"`
+	Size        int        `xml:"size,attr,omitempty"        json:"size,omitempty"`
+	Suffix      string     `xml:"suffix,attr,omitempty"      json:"suffix,omitempty"`
+	Title       string     `xml:"title,attr"                 json:"title"`
+	TrackNumber int        `xml:"track,attr,omitempty"       json:"track,omitempty"`
+	DiscNumber  int        `xml:"discNumber,attr,omitempty"  json:"discNumber,omitempty"`
+	Type        string     `xml:"type,attr,omitempty"        json:"type,omitempty"`
 }
 
 type Artists struct {
@@ -148,11 +148,11 @@ type Artists struct {
 }
 
 type Artist struct {
-	ID         specid.ID `xml:"id,attr,omitempty"       json:"id"`
-	Name       string    `xml:"name,attr"               json:"name"`
-	CoverID    specid.ID `xml:"coverArt,attr,omitempty" json:"coverArt,omitempty"`
-	AlbumCount int       `xml:"albumCount,attr"         json:"albumCount"`
-	Albums     []*Album  `xml:"album,omitempty"         json:"album,omitempty"`
+	ID         *specid.ID `xml:"id,attr,omitempty"       json:"id"`
+	Name       string     `xml:"name,attr"               json:"name"`
+	CoverID    *specid.ID `xml:"coverArt,attr,omitempty" json:"coverArt,omitempty"`
+	AlbumCount int        `xml:"albumCount,attr"         json:"albumCount"`
+	Albums     []*Album   `xml:"album,omitempty"         json:"album,omitempty"`
 }
 
 type Indexes struct {
@@ -167,8 +167,8 @@ type Index struct {
 }
 
 type Directory struct {
-	ID       specid.ID     `xml:"id,attr,omitempty"      json:"id"`
-	ParentID specid.ID     `xml:"parent,attr,omitempty"  json:"parent,omitempty"`
+	ID       *specid.ID    `xml:"id,attr,omitempty"      json:"id"`
+	ParentID *specid.ID    `xml:"parent,attr,omitempty"  json:"parent,omitempty"`
 	Name     string        `xml:"name,attr,omitempty"    json:"name"`
 	Starred  string        `xml:"starred,attr,omitempty" json:"starred,omitempty"`
 	Children []*TrackChild `xml:"child,omitempty"        json:"child,omitempty"`
@@ -239,9 +239,9 @@ type Playlist struct {
 }
 
 type SimilarArtist struct {
-	ID         specid.ID `xml:"id,attr"                   json:"id"`
-	Name       string    `xml:"name,attr"                 json:"name"`
-	AlbumCount int       `xml:"albumCount,attr,omitempty" json:"albumCount,omitempty"`
+	ID         *specid.ID `xml:"id,attr"                   json:"id"`
+	Name       string     `xml:"name,attr"                 json:"name"`
+	AlbumCount int        `xml:"albumCount,attr,omitempty" json:"albumCount,omitempty"`
 }
 
 type ArtistInfo struct {
diff --git a/server/db/model.go b/server/db/model.go
index 37ecf06..7dfab99 100644
--- a/server/db/model.go
+++ b/server/db/model.go
@@ -49,8 +49,8 @@ type Artist struct {
 	AlbumCount int      `sql:"-"`
 }
 
-func (a *Artist) SID() specid.ID {
-	return specid.ID{Type: specid.Artist, Value: a.ID}
+func (a *Artist) SID() *specid.ID {
+	return &specid.ID{Type: specid.Artist, Value: a.ID}
 }
 
 func (a *Artist) IndexName() string {
@@ -92,16 +92,16 @@ type Track struct {
 	TagBrainzID    string `sql:"default: null"`
 }
 
-func (t *Track) SID() specid.ID {
-	return specid.ID{Type: specid.Track, Value: t.ID}
+func (t *Track) SID() *specid.ID {
+	return &specid.ID{Type: specid.Track, Value: t.ID}
 }
 
-func (t *Track) AlbumSID() specid.ID {
-	return specid.ID{Type: specid.Album, Value: t.AlbumID}
+func (t *Track) AlbumSID() *specid.ID {
+	return &specid.ID{Type: specid.Album, Value: t.AlbumID}
 }
 
-func (t *Track) ArtistSID() specid.ID {
-	return specid.ID{Type: specid.Artist, Value: t.ArtistID}
+func (t *Track) ArtistSID() *specid.ID {
+	return &specid.ID{Type: specid.Artist, Value: t.ArtistID}
 }
 
 func (t *Track) Ext() string {
@@ -176,12 +176,12 @@ type Album struct {
 	ReceivedTags  bool `gorm:"-"`
 }
 
-func (a *Album) SID() specid.ID {
-	return specid.ID{Type: specid.Album, Value: a.ID}
+func (a *Album) SID() *specid.ID {
+	return &specid.ID{Type: specid.Album, Value: a.ID}
 }
 
-func (a *Album) ParentSID() specid.ID {
-	return specid.ID{Type: specid.Album, Value: a.ParentID}
+func (a *Album) ParentSID() *specid.ID {
+	return &specid.ID{Type: specid.Album, Value: a.ParentID}
 }
 
 func (a *Album) IndexRightPath() string {