diff --git a/dependencies.gradle b/dependencies.gradle
index 7a5c0375..243712c2 100644
--- a/dependencies.gradle
+++ b/dependencies.gradle
@@ -18,7 +18,7 @@ ext.versions = [
 
         kotlin               : "1.2.31",
 
-        retrofit             : "2.1.0",
+        retrofit             : "2.4.0",
         jackson              : "2.9.0",
         okhttp               : "3.9.0",
         semver               : "1.0.0",
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/CommonFunctions.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/CommonFunctions.kt
index 7ee3bcc4..deca2f70 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/CommonFunctions.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/CommonFunctions.kt
@@ -64,11 +64,11 @@ fun <T : SubsonicResponse> checkErrorCallParsed(mockWebServerRule: MockWebServer
     val response = apiRequest()
 
     assertResponseSuccessful(response)
-    with(response.body()) {
+    with(response.body()!!) {
         status `should be` SubsonicResponse.Status.ERROR
         error `should be` SubsonicError.RequestedDataWasNotFound
     }
-    return response.body()
+    return response.body()!!
 }
 
 fun SubsonicResponse.assertBaseResponseOk() {
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiCreateShareTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiCreateShareTest.kt
index 82f95769..ed699f46 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiCreateShareTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiCreateShareTest.kt
@@ -26,8 +26,8 @@ class SubsonicApiCreateShareTest : SubsonicAPIClientTest() {
         val response = client.api.createShare(listOf("some-id")).execute()
 
         assertResponseSuccessful(response)
-        response.body().shares.size `should equal to` 1
-        with(response.body().shares[0]) {
+        response.body()!!.shares.size `should equal to` 1
+        with(response.body()!!.shares[0]) {
             id `should equal to` "0"
             url `should equal to` "https://subsonic.com/ext/share/awdwo?jwt=eyJhbGciOiJIUzI1NiJ9." +
                     "eyJwYXRoIjoiL2V4dC9zaGFyZS9hd2R3byIsImV4cCI6MTU0MTYyNjQzMX0.iy8dkt_ZZc8hJ692" +
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiErrorsTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiErrorsTest.kt
index 3b8c66f9..947c7c22 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiErrorsTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiErrorsTest.kt
@@ -150,7 +150,7 @@ class SubsonicApiErrorsTest : SubsonicAPIClientTest() {
     }
 
     private fun Response<SubsonicResponse>.assertError(expectedError: SubsonicError) =
-            with(body()) {
+            with(body()!!) {
                 error `should not be` null
                 error `should equal` expectedError
             }
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumList2Test.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumList2Test.kt
index 817a9f36..c7ca56fb 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumList2Test.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumList2Test.kt
@@ -28,7 +28,7 @@ class SubsonicApiGetAlbumList2Test : SubsonicAPIClientTest() {
         val response = client.api.getAlbumList2(STARRED).execute()
 
         assertResponseSuccessful(response)
-        with(response.body().albumList) {
+        with(response.body()!!.albumList) {
             this.size `should equal to` 2
             this[0] `should equal` Album(id = "962", name = "Fury", artist = "Sick Puppies",
                     artistId = "473", coverArt = "al-962", songCount = 13, duration = 2591,
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumListRequestTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumListRequestTest.kt
index eb2ffb6f..72bb3934 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumListRequestTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumListRequestTest.kt
@@ -27,7 +27,7 @@ class SubsonicApiGetAlbumListRequestTest : SubsonicAPIClientTest() {
         val response = client.api.getAlbumList(BY_GENRE).execute()
 
         assertResponseSuccessful(response)
-        with(response.body().albumList) {
+        with(response.body()!!.albumList) {
             size `should equal to` 2
             this[1] `should equal` MusicDirectoryChild(id = "9997", parent = "9996", isDir = true,
                     title = "Endless Forms Most Beautiful", album = "Endless Forms Most Beautiful",
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumTest.kt
index 32793390..55dfd8df 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetAlbumTest.kt
@@ -38,7 +38,7 @@ class SubsonicApiGetAlbumTest : SubsonicAPIClientTest() {
         val response = client.api.getAlbum("512").execute()
 
         assertResponseSuccessful(response)
-        with(response.body().album) {
+        with(response.body()!!.album) {
             id `should equal to` "618"
             name `should equal to` "Black Ice"
             artist `should equal to` "AC/DC"
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistTest.kt
index 5904ee6c..2979453b 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistTest.kt
@@ -38,7 +38,7 @@ class SubsonicApiGetArtistTest : SubsonicAPIClientTest() {
         val response = client.api.getArtist("100").execute()
 
         assertResponseSuccessful(response)
-        with(response.body().artist) {
+        with(response.body()!!.artist) {
             id `should equal to` "362"
             name `should equal to` "AC/DC"
             coverArt `should equal to` "ar-362"
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistsTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistsTest.kt
index 100042c5..9a504b71 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistsTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetArtistsTest.kt
@@ -29,7 +29,7 @@ class SubsonicApiGetArtistsTest : SubsonicAPIClientTest() {
         val response = client.api.getArtists(null).execute()
 
         assertResponseSuccessful(response)
-        with(response.body().indexes) {
+        with(response.body()!!.indexes) {
             lastModified `should equal to` 0L
             ignoredArticles `should equal to` "The El La Los Las Le Les"
             shortcutList `should equal` emptyList()
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetBookmarksTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetBookmarksTest.kt
index a10070ee..dea42311 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetBookmarksTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetBookmarksTest.kt
@@ -25,8 +25,8 @@ class SubsonicApiGetBookmarksTest : SubsonicAPIClientTest() {
         val response = client.api.getBookmarks().execute()
 
         assertResponseSuccessful(response)
-        response.body().bookmarkList.size `should equal to` 1
-        with(response.body().bookmarkList[0]) {
+        response.body()!!.bookmarkList.size `should equal to` 1
+        with(response.body()!!.bookmarkList[0]) {
             position `should equal to` 107914
             username `should equal to` "CaptainEurope"
             comment `should equal to` "Look at this"
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetChatMessagesTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetChatMessagesTest.kt
index 910c58a0..b7adae46 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetChatMessagesTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetChatMessagesTest.kt
@@ -25,7 +25,7 @@ class SubsonicApiGetChatMessagesTest : SubsonicAPIClientTest() {
         val response = client.api.getChatMessages().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().chatMessages) {
+        with(response.body()!!.chatMessages) {
             size `should equal to` 2
             this[0] `should equal` ChatMessage(username = "sindre", time = 1269771845310,
                     message = "Sindre was here")
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetGenresTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetGenresTest.kt
index 1f311f07..722fb2e3 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetGenresTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetGenresTest.kt
@@ -25,7 +25,7 @@ class SubsonicApiGetGenresTest : SubsonicAPIClientTest() {
         val response = client.api.getGenres().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().genresList) {
+        with(response.body()!!.genresList) {
             size `should equal to` 5
             this[0] `should equal` Genre(1186, 103, "Rock")
             this[1] `should equal` Genre(896, 72, "Electronic")
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetIndexesTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetIndexesTest.kt
index b9bbc34c..5f1ac659 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetIndexesTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetIndexesTest.kt
@@ -18,8 +18,8 @@ class SubsonicApiGetIndexesTest : SubsonicAPIClientTest() {
         val response = client.api.getIndexes(null, null).execute()
 
         assertResponseSuccessful(response)
-        response.body().indexes `should not be` null
-        with(response.body().indexes) {
+        response.body()!!.indexes `should not be` null
+        with(response.body()!!.indexes) {
             lastModified `should equal` 1491069027523
             ignoredArticles `should equal` "The El La Los Las Le Les"
             shortcutList `should equal` listOf(
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLicenseTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLicenseTest.kt
index 21401094..d0ca9eb8 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLicenseTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLicenseTest.kt
@@ -16,7 +16,7 @@ class SubsonicApiGetLicenseTest : SubsonicAPIClientTest() {
         val response = client.api.getLicense().execute()
 
         assertResponseSuccessful(response)
-        with(response.body()) {
+        with(response.body()!!) {
             assertBaseResponseOk()
             license `should equal` License(valid = true,
                     trialExpires = parseDate("2016-11-23T20:17:15.206Z"),
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLyricsTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLyricsTest.kt
index a5d29b57..31de56e6 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLyricsTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetLyricsTest.kt
@@ -21,7 +21,7 @@ class SubsonicApiGetLyricsTest : SubsonicAPIClientTest() {
         val response = client.api.getLyrics().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().lyrics) {
+        with(response.body()!!.lyrics) {
             artist `should equal to` "Amorphis"
             title `should equal to` "Alone"
             text `should equal to` "Tear dimmed rememberance\nIn a womb of time\nBreath upon " +
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicDirectoryTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicDirectoryTest.kt
index 0801e673..0b7da0a5 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicDirectoryTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicDirectoryTest.kt
@@ -40,8 +40,8 @@ class SubsonicApiGetMusicDirectoryTest : SubsonicAPIClientTest() {
 
         assertResponseSuccessful(response)
 
-        response.body().musicDirectory `should not be` null
-        with(response.body().musicDirectory) {
+        response.body()!!.musicDirectory `should not be` null
+        with(response.body()!!.musicDirectory) {
             id `should equal to` "4836"
             parent `should equal to` "300"
             name `should equal` "12 Stones"
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicFoldersTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicFoldersTest.kt
index c3460aed..0ccfde1d 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicFoldersTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetMusicFoldersTest.kt
@@ -15,7 +15,7 @@ class SubsonicApiGetMusicFoldersTest : SubsonicAPIClientTest() {
         val response = client.api.getMusicFolders().execute()
 
         assertResponseSuccessful(response)
-        with(response.body()) {
+        with(response.body()!!) {
             assertBaseResponseOk()
             musicFolders `should equal` listOf(
                     MusicFolder("0", "Music"),
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistTest.kt
index d542d0db..fff9fe29 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistTest.kt
@@ -28,7 +28,7 @@ class SubsonicApiGetPlaylistTest : SubsonicAPIClientTest() {
         val response = client.api.getPlaylist("4").execute()
 
         assertResponseSuccessful(response)
-        with(response.body().playlist) {
+        with(response.body()!!.playlist) {
             id `should equal to` "0"
             name `should equal to` "Aug 27, 2017 11:17 AM"
             owner `should equal to` "admin"
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistsTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistsTest.kt
index f787c37c..e55df742 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistsTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPlaylistsTest.kt
@@ -27,7 +27,7 @@ class SubsonicApiGetPlaylistsTest : SubsonicAPIClientTest() {
         val response = client.api.getPlaylists().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().playlists) {
+        with(response.body()!!.playlists) {
             size `should equal to` 1
             this[0] `should equal` Playlist(id = "0", name = "Aug 27, 2017 11:17 AM",
                     owner = "admin", public = false, songCount = 16, duration = 3573,
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPodcastsTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPodcastsTest.kt
index 985425e4..1420f58a 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPodcastsTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetPodcastsTest.kt
@@ -27,7 +27,7 @@ class SubsonicApiGetPodcastsTest : SubsonicAPIClientTest() {
         val response = client.api.getPodcasts().execute()
 
         assertResponseSuccessful(response)
-        val podcastChannelsList = response.body().podcastChannels
+        val podcastChannelsList = response.body()!!.podcastChannels
         podcastChannelsList.size `should equal to` 1
         with(podcastChannelsList[0]) {
             id `should equal to` "2"
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetRandomSongsTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetRandomSongsTest.kt
index 8f06b174..eec95522 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetRandomSongsTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetRandomSongsTest.kt
@@ -25,7 +25,7 @@ class SubsonicApiGetRandomSongsTest : SubsonicAPIClientTest() {
         val response = client.api.getRandomSongs().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().songsList) {
+        with(response.body()!!.songsList) {
             size `should equal to` 3
             this[1] `should equal` MusicDirectoryChild(id = "3061", parent = "3050", isDir = false,
                     title = "Sure as Hell", album = "Who Are You Now?", artist = "This Providence",
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSharesTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSharesTest.kt
index 6da16b43..dc791aa8 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSharesTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSharesTest.kt
@@ -25,8 +25,8 @@ class SubsonicApiGetSharesTest : SubsonicAPIClientTest() {
         val response = client.api.getShares().execute()
 
         assertResponseSuccessful(response)
-        response.body().shares.size `should equal to` 1
-        with(response.body().shares[0]) {
+        response.body()!!.shares.size `should equal to` 1
+        with(response.body()!!.shares[0]) {
             id `should equal to` "0"
             url `should equal to` "https://subsonic.com/ext/share/awdwo?jwt=eyJhbGciOiJIUzI1" +
                     "NiJ9.eyJwYXRoIjoiL2V4dC9zaGFyZS9hd2R3byIsImV4cCI6MTU0MTYyNjQzMX0.iy8dkt_ZZc8" +
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSongsByGenreTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSongsByGenreTest.kt
index c344c8b3..a3d474fc 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSongsByGenreTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSongsByGenreTest.kt
@@ -25,8 +25,8 @@ class SubsonicApiGetSongsByGenreTest : SubsonicAPIClientTest() {
         val response = client.api.getSongsByGenre("Trance").execute()
 
         assertResponseSuccessful(response)
-        response.body().songsList.size `should equal to` 2
-        with(response.body().songsList) {
+        response.body()!!.songsList.size `should equal to` 2
+        with(response.body()!!.songsList) {
             this[0] `should equal` MusicDirectoryChild(id = "575", parent = "576", isDir = false,
                     title = "Time Machine (Vadim Zhukov Remix)", album = "668",
                     artist = "Tasadi", year = 2008, genre = "Trance", size = 22467672,
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarred2Test.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarred2Test.kt
index b8409cd0..a77ad81e 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarred2Test.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarred2Test.kt
@@ -27,7 +27,7 @@ class SubsonicApiGetStarred2Test : SubsonicAPIClientTest() {
         val response = client.api.getStarred2().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().starred2) {
+        with(response.body()!!.starred2) {
             albumList `should equal` emptyList()
             artistList.size `should equal to` 1
             artistList[0] `should equal` Artist(id = "364", name = "Parov Stelar",
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarredTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarredTest.kt
index 3fd5fb9c..8a41f90c 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarredTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetStarredTest.kt
@@ -26,7 +26,7 @@ class SubsonicApiGetStarredTest : SubsonicAPIClientTest() {
         val response = client.api.getStarred().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().starred) {
+        with(response.body()!!.starred) {
             albumList `should equal` emptyList()
             artistList.size `should equal to` 1
             artistList[0] `should equal` Artist(id = "364", name = "Parov Stelar",
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetUserTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetUserTest.kt
index 648cbeae..709c0de0 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetUserTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetUserTest.kt
@@ -25,7 +25,7 @@ class SubsonicApiGetUserTest : SubsonicAPIClientTest() {
         val response = client.api.getUser("some").execute()
 
         assertResponseSuccessful(response)
-        with(response.body().user) {
+        with(response.body()!!.user) {
             username `should equal to` "GodOfUniverse"
             email `should equal to` "some.mail@example.com"
             scrobblingEnabled `should equal to` false
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetVideosListTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetVideosListTest.kt
index ef3d71ab..d11e7d58 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetVideosListTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetVideosListTest.kt
@@ -25,7 +25,7 @@ class SubsonicApiGetVideosListTest : SubsonicAPIClientTest() {
         val response = client.api.getVideos().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().videosList) {
+        with(response.body()!!.videosList) {
             size `should equal to` 1
             this[0] `should equal` MusicDirectoryChild(id = "10402", parent = "10401",
                     isDir = false, title = "MVI_0512", album = "Incoming", size = 21889646,
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiJukeboxControlTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiJukeboxControlTest.kt
index d072a217..70f83daa 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiJukeboxControlTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiJukeboxControlTest.kt
@@ -29,7 +29,7 @@ class SubsonicApiJukeboxControlTest : SubsonicAPIClientTest() {
         val response = client.api.jukeboxControl(STATUS).execute()
 
         assertResponseSuccessful(response)
-        with(response.body().jukebox) {
+        with(response.body()!!.jukebox) {
             currentIndex `should equal to` 94
             playing `should equal to` true
             gain `should equal to` 0.32f
@@ -45,7 +45,7 @@ class SubsonicApiJukeboxControlTest : SubsonicAPIClientTest() {
         val response = client.api.jukeboxControl(GET).execute()
 
         assertResponseSuccessful(response)
-        with(response.body().jukebox) {
+        with(response.body()!!.jukebox) {
             currentIndex `should equal to` 887
             playing `should equal to` false
             gain `should equal to` 0.88f
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiPingRequestTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiPingRequestTest.kt
index b157ef40..055d91fa 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiPingRequestTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiPingRequestTest.kt
@@ -13,7 +13,7 @@ class SubsonicApiPingRequestTest : SubsonicAPIClientTest() {
         val response = client.api.ping().execute()
 
         assertResponseSuccessful(response)
-        with(response.body()) {
+        with(response.body()!!) {
             assertBaseResponseOk()
         }
     }
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTest.kt
index cd850480..eacf7eb0 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTest.kt
@@ -29,7 +29,7 @@ class SubsonicApiSearchTest : SubsonicAPIClientTest() {
         val response = client.api.search().execute()
 
         assertResponseSuccessful(response)
-        with(response.body().searchResult) {
+        with(response.body()!!.searchResult) {
             offset `should equal to` 10
             totalHits `should equal to` 53
             matchList.size `should equal to` 1
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchThreeTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchThreeTest.kt
index e9aca121..77fe806d 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchThreeTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchThreeTest.kt
@@ -30,7 +30,7 @@ class SubsonicApiSearchThreeTest : SubsonicAPIClientTest() {
         val response = client.api.search3("some-query").execute()
 
         assertResponseSuccessful(response)
-        with(response.body().searchResult) {
+        with(response.body()!!.searchResult) {
             artistList.size `should equal to` 1
             artistList[0] `should equal` Artist(id = "505", name = "The Prodigy",
                     coverArt = "ar-505", albumCount = 5)
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTwoTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTwoTest.kt
index e572090f..38e5bb3b 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTwoTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiSearchTwoTest.kt
@@ -29,7 +29,7 @@ class SubsonicApiSearchTwoTest : SubsonicAPIClientTest() {
         val response = client.api.search2("some-query").execute()
 
         assertResponseSuccessful(response)
-        with(response.body().searchResult) {
+        with(response.body()!!.searchResult) {
             artistList.size `should equal to` 1
             artistList[0] `should equal` Artist(id = "522", name = "The Prodigy")
             albumList.size `should equal to` 1
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiStarTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiStarTest.kt
index 12377e3d..7ed24e26 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiStarTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiStarTest.kt
@@ -15,7 +15,7 @@ class SubsonicApiStarTest : SubsonicAPIClientTest() {
         val response = client.api.star().execute()
 
         assertResponseSuccessful(response)
-        response.body().status `should be` SubsonicResponse.Status.OK
+        response.body()?.status `should be` SubsonicResponse.Status.OK
     }
 
     @Test
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiUnstarTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiUnstarTest.kt
index a47a120a..26ec548e 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiUnstarTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiUnstarTest.kt
@@ -15,7 +15,7 @@ class SubsonicApiUnstarTest : SubsonicAPIClientTest() {
         val response = client.api.unstar().execute()
 
         assertResponseSuccessful(response)
-        response.body().status `should be` SubsonicResponse.Status.OK
+        response.body()?.status `should be` SubsonicResponse.Status.OK
     }
 
     @Test
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClient.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClient.kt
index fa1c1cd2..36f024b3 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClient.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClient.kt
@@ -139,14 +139,14 @@ class SubsonicAPIClient(baseUrl: String,
         val response = apiCall()
         return if (response.isSuccessful) {
             val responseBody = response.body()
-            val contentType = responseBody.contentType()
+            val contentType = responseBody?.contentType()
             if (contentType != null &&
                     contentType.type().equals("application", true) &&
                     contentType.subtype().equals("json", true)) {
                 val error = jacksonMapper.readValue<SubsonicResponse>(responseBody.byteStream())
                 StreamResponse(apiError = error.error, responseHttpCode = response.code())
             } else {
-                StreamResponse(stream = responseBody.byteStream(),
+                StreamResponse(stream = responseBody?.byteStream(),
                         responseHttpCode = response.code())
             }
         } else {
@@ -165,7 +165,7 @@ class SubsonicAPIClient(baseUrl: String,
         val request = api.stream(id).execute()
         val url = request.raw().request().url().toString()
         if (request.isSuccessful) {
-            request.body().close()
+            request.body()?.close()
         }
         return url
     }
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/PasswordHexInterceptor.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/PasswordHexInterceptor.kt
index bec49519..a6c8b853 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/PasswordHexInterceptor.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/PasswordHexInterceptor.kt
@@ -19,7 +19,7 @@ class PasswordHexInterceptor(private val password: String) : Interceptor {
     override fun intercept(chain: Chain): Response {
         val originalRequest = chain.request()
         val updatedUrl = originalRequest.url().newBuilder()
-                .addQueryParameter("p", passwordHex).build()
+                .addEncodedQueryParameter("p", passwordHex).build()
         return chain.proceed(originalRequest.newBuilder().url(updatedUrl).build())
     }
 }