diff --git a/audio/src/fetch.rs b/audio/src/fetch.rs
index f9bd11a9..1455f21b 100644
--- a/audio/src/fetch.rs
+++ b/audio/src/fetch.rs
@@ -11,7 +11,7 @@ use tempfile::NamedTempFile;
 
 use core::channel::{Channel, ChannelData, ChannelError, ChannelHeaders};
 use core::session::Session;
-use core::util::FileId;
+use core::spotify_id::FileId;
 
 const CHUNK_SIZE: usize = 0x20000;
 
@@ -115,7 +115,7 @@ impl Future for AudioFileOpenStreaming {
             if id == 0x3 {
                 let size = BigEndian::read_u32(&data) as usize * 4;
                 let file = self.finish(size);
-                
+
                 return Ok(Async::Ready(file));
             }
         }
diff --git a/connect/src/spirc.rs b/connect/src/spirc.rs
index 704472d7..2b88249c 100644
--- a/connect/src/spirc.rs
+++ b/connect/src/spirc.rs
@@ -6,7 +6,8 @@ use protobuf::{self, Message};
 use core::config::ConnectConfig;
 use core::mercury::MercuryError;
 use core::session::Session;
-use core::util::{SeqGenerator, SpotifyId};
+use core::spotify_id::SpotifyId;
+use core::util::SeqGenerator;
 use core::version;
 
 use protocol;
diff --git a/core/src/audio_key.rs b/core/src/audio_key.rs
index 2d4fb2ab..021b1dc8 100644
--- a/core/src/audio_key.rs
+++ b/core/src/audio_key.rs
@@ -5,7 +5,7 @@ use futures::sync::oneshot;
 use std::collections::HashMap;
 use std::io::Write;
 
-use util::{FileId, SpotifyId};
+use spotify_id::{FileId, SpotifyId};
 use util::SeqGenerator;
 
 #[derive(Debug, Hash, PartialEq, Eq, Copy, Clone)]
diff --git a/core/src/cache.rs b/core/src/cache.rs
index fb59c729..a5f89d5e 100644
--- a/core/src/cache.rs
+++ b/core/src/cache.rs
@@ -6,7 +6,7 @@ use std::path::Path;
 use std::path::PathBuf;
 
 use authentication::Credentials;
-use util::FileId;
+use spotify_id::FileId;
 
 #[derive(Clone)]
 pub struct Cache {
diff --git a/core/src/component.rs b/core/src/component.rs
index 923e72ec..50ab7b37 100644
--- a/core/src/component.rs
+++ b/core/src/component.rs
@@ -4,7 +4,7 @@ macro_rules! component {
         pub struct $name(::std::sync::Arc<($crate::session::SessionWeak, ::std::sync::Mutex<$inner>)>);
         impl $name {
             #[allow(dead_code)]
-            pub fn new(session: $crate::session::SessionWeak) -> $name {
+            pub(crate) fn new(session: $crate::session::SessionWeak) -> $name {
                 debug!(target:"librespot::component", "new {}", stringify!($name));
 
                 $name(::std::sync::Arc::new((session, ::std::sync::Mutex::new($inner {
@@ -39,17 +39,17 @@ macro_rules! component {
 use std::cell::UnsafeCell;
 use std::sync::Mutex;
 
-pub struct Lazy<T>(Mutex<bool>, UnsafeCell<Option<T>>);
+pub(crate) struct Lazy<T>(Mutex<bool>, UnsafeCell<Option<T>>);
 unsafe impl<T: Sync> Sync for Lazy<T> {}
 unsafe impl<T: Send> Send for Lazy<T> {}
 
 #[cfg_attr(feature = "cargo-clippy", allow(mutex_atomic))]
 impl<T> Lazy<T> {
-    pub fn new() -> Lazy<T> {
+    pub(crate) fn new() -> Lazy<T> {
         Lazy(Mutex::new(false), UnsafeCell::new(None))
     }
 
-    pub fn get<F: FnOnce() -> T>(&self, f: F) -> &T {
+    pub(crate) fn get<F: FnOnce() -> T>(&self, f: F) -> &T {
         let mut inner = self.0.lock().unwrap();
         if !*inner {
             unsafe {
diff --git a/core/src/lib.rs b/core/src/lib.rs
index 207c7656..3c9be131 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -44,5 +44,6 @@ pub mod diffie_hellman;
 pub mod keymaster;
 pub mod mercury;
 pub mod session;
+pub mod spotify_id;
 pub mod util;
 pub mod version;
diff --git a/core/src/mercury/mod.rs b/core/src/mercury/mod.rs
index 9a607061..e79c281f 100644
--- a/core/src/mercury/mod.rs
+++ b/core/src/mercury/mod.rs
@@ -51,7 +51,7 @@ impl MercuryManager {
         seq
     }
 
-    pub fn request(&self, req: MercuryRequest) -> MercuryFuture<MercuryResponse> {
+    fn request(&self, req: MercuryRequest) -> MercuryFuture<MercuryResponse> {
         let (tx, rx) = oneshot::channel();
 
         let pending = MercuryPending {
diff --git a/core/src/session.rs b/core/src/session.rs
index 628e0377..cb210a0f 100644
--- a/core/src/session.rs
+++ b/core/src/session.rs
@@ -19,12 +19,12 @@ use audio_key::AudioKeyManager;
 use channel::ChannelManager;
 use mercury::MercuryManager;
 
-pub struct SessionData {
+struct SessionData {
     country: String,
     canonical_username: String,
 }
 
-pub struct SessionInternal {
+struct SessionInternal {
     config: SessionConfig,
     data: RwLock<SessionData>,
 
@@ -43,7 +43,7 @@ pub struct SessionInternal {
 static SESSION_COUNTER: AtomicUsize = ATOMIC_USIZE_INIT;
 
 #[derive(Clone)]
-pub struct Session(pub Arc<SessionInternal>);
+pub struct Session(Arc<SessionInternal>);
 
 pub fn device_id(name: &str) -> String {
     let mut h = Sha1::new();
@@ -226,7 +226,7 @@ impl Session {
 }
 
 #[derive(Clone)]
-pub struct SessionWeak(pub Weak<SessionInternal>);
+pub struct SessionWeak(Weak<SessionInternal>);
 
 impl SessionWeak {
     fn try_upgrade(&self) -> Option<Session> {
diff --git a/core/src/util/spotify_id.rs b/core/src/spotify_id.rs
similarity index 100%
rename from core/src/util/spotify_id.rs
rename to core/src/spotify_id.rs
diff --git a/core/src/util/mod.rs b/core/src/util/mod.rs
index 66f2fe3f..9c373eaa 100644
--- a/core/src/util/mod.rs
+++ b/core/src/util/mod.rs
@@ -6,10 +6,8 @@ use std::mem;
 use std::ops::{Mul, Rem, Shr};
 
 mod int128;
-mod spotify_id;
 
 pub use util::int128::u128;
-pub use util::spotify_id::{FileId, SpotifyId};
 
 pub fn rand_vec<G: Rng, R: Rand>(rng: &mut G, size: usize) -> Vec<R> {
     rng.gen_iter().take(size).collect()
@@ -31,32 +29,6 @@ pub fn powm(base: &BigUint, exp: &BigUint, modulus: &BigUint) -> BigUint {
     result
 }
 
-pub struct StrChunks<'s>(&'s str, usize);
-
-pub trait StrChunksExt {
-    fn chunks(&self, size: usize) -> StrChunks;
-}
-
-impl StrChunksExt for str {
-    fn chunks(&self, size: usize) -> StrChunks {
-        StrChunks(self, size)
-    }
-}
-
-impl<'s> Iterator for StrChunks<'s> {
-    type Item = &'s str;
-    fn next(&mut self) -> Option<&'s str> {
-        let &mut StrChunks(data, size) = self;
-        if data.is_empty() {
-            None
-        } else {
-            let ret = Some(&data[..size]);
-            self.0 = &data[size..];
-            ret
-        }
-    }
-}
-
 pub trait ReadSeek: ::std::io::Read + ::std::io::Seek {}
 impl<T: ::std::io::Read + ::std::io::Seek> ReadSeek for T {}
 
diff --git a/examples/play.rs b/examples/play.rs
index 8c88ddbe..2c0b3282 100644
--- a/examples/play.rs
+++ b/examples/play.rs
@@ -7,7 +7,7 @@ use tokio_core::reactor::Core;
 use librespot::core::authentication::Credentials;
 use librespot::playback::config::{PlayerConfig, SessionConfig};
 use librespot::core::session::Session;
-use librespot::core::util::SpotifyId;
+use librespot::core::spotify_id::SpotifyId;
 
 use librespot::audio_backend;
 use librespot::player::Player;
diff --git a/metadata/src/cover.rs b/metadata/src/cover.rs
index ea3c197b..0ef186a0 100644
--- a/metadata/src/cover.rs
+++ b/metadata/src/cover.rs
@@ -3,7 +3,7 @@ use std::io::Write;
 
 use core::channel::ChannelData;
 use core::session::Session;
-use core::util::FileId;
+use core::spotify_id::FileId;
 
 pub fn get(session: &Session, file: FileId) -> ChannelData {
     let (channel_id, channel) = session.channel().allocate();
diff --git a/metadata/src/lib.rs b/metadata/src/lib.rs
index 2439ded6..0103a3b0 100644
--- a/metadata/src/lib.rs
+++ b/metadata/src/lib.rs
@@ -13,7 +13,7 @@ use linear_map::LinearMap;
 
 use core::mercury::MercuryError;
 use core::session::Session;
-use core::util::{SpotifyId, FileId, StrChunksExt};
+use core::spotify_id::{FileId, SpotifyId};
 
 pub use protocol::metadata::AudioFile_Format as FileFormat;
 
@@ -22,7 +22,8 @@ fn countrylist_contains(list: &str, country: &str) -> bool {
 }
 
 fn parse_restrictions<'s, I>(restrictions: I, country: &str, catalogue: &str) -> bool
-    where I: IntoIterator<Item = &'s protocol::metadata::Restriction>
+where
+    I: IntoIterator<Item = &'s protocol::metadata::Restriction>,
 {
     let mut forbidden = "".to_string();
     let mut has_forbidden = false;
@@ -30,9 +31,9 @@ fn parse_restrictions<'s, I>(restrictions: I, country: &str, catalogue: &str) ->
     let mut allowed = "".to_string();
     let mut has_allowed = false;
 
-    let rs = restrictions.into_iter().filter(|r|
-        r.get_catalogue_str().contains(&catalogue.to_owned())
-    );
+    let rs = restrictions
+        .into_iter()
+        .filter(|r| r.get_catalogue_str().contains(&catalogue.to_owned()));
 
     for r in rs {
         if r.has_countries_forbidden() {
@@ -46,12 +47,12 @@ fn parse_restrictions<'s, I>(restrictions: I, country: &str, catalogue: &str) ->
         }
     }
 
-    (has_forbidden || has_allowed) &&
-    (!has_forbidden || !countrylist_contains(forbidden.as_str(), country)) &&
-    (!has_allowed || countrylist_contains(allowed.as_str(), country))
+    (has_forbidden || has_allowed)
+        && (!has_forbidden || !countrylist_contains(forbidden.as_str(), country))
+        && (!has_allowed || countrylist_contains(allowed.as_str(), country))
 }
 
-pub trait Metadata : Send + Sized + 'static {
+pub trait Metadata: Send + Sized + 'static {
     type Message: protobuf::MessageStatic;
 
     fn base_url() -> &'static str;
@@ -110,20 +111,20 @@ impl Metadata for Track {
         let country = session.country();
 
         let artists = msg.get_artist()
-                         .iter()
-                         .filter(|artist| artist.has_gid())
-                         .map(|artist| SpotifyId::from_raw(artist.get_gid()))
-                         .collect::<Vec<_>>();
+            .iter()
+            .filter(|artist| artist.has_gid())
+            .map(|artist| SpotifyId::from_raw(artist.get_gid()))
+            .collect::<Vec<_>>();
 
         let files = msg.get_file()
-                       .iter()
-                       .filter(|file| file.has_file_id())
-                       .map(|file| {
-                           let mut dst = [0u8; 20];
-                           dst.clone_from_slice(file.get_file_id());
-                           (file.get_format(), FileId(dst))
-                       })
-                       .collect();
+            .iter()
+            .filter(|file| file.has_file_id())
+            .map(|file| {
+                let mut dst = [0u8; 20];
+                dst.clone_from_slice(file.get_file_id());
+                (file.get_format(), FileId(dst))
+            })
+            .collect();
 
         Track {
             id: SpotifyId::from_raw(msg.get_gid()),
@@ -133,12 +134,10 @@ impl Metadata for Track {
             artists: artists,
             files: files,
             alternatives: msg.get_alternative()
-                             .iter()
-                             .map(|alt| SpotifyId::from_raw(alt.get_gid()))
-                             .collect(),
-            available: parse_restrictions(msg.get_restriction(),
-                                          &country,
-                                          "premium"),
+                .iter()
+                .map(|alt| SpotifyId::from_raw(alt.get_gid()))
+                .collect(),
+            available: parse_restrictions(msg.get_restriction(), &country, "premium"),
         }
     }
 }
@@ -152,28 +151,28 @@ impl Metadata for Album {
 
     fn parse(msg: &Self::Message, _: &Session) -> Self {
         let artists = msg.get_artist()
-                         .iter()
-                         .filter(|artist| artist.has_gid())
-                         .map(|artist| SpotifyId::from_raw(artist.get_gid()))
-                         .collect::<Vec<_>>();
+            .iter()
+            .filter(|artist| artist.has_gid())
+            .map(|artist| SpotifyId::from_raw(artist.get_gid()))
+            .collect::<Vec<_>>();
 
         let tracks = msg.get_disc()
-                        .iter()
-                        .flat_map(|disc| disc.get_track())
-                        .filter(|track| track.has_gid())
-                        .map(|track| SpotifyId::from_raw(track.get_gid()))
-                        .collect::<Vec<_>>();
+            .iter()
+            .flat_map(|disc| disc.get_track())
+            .filter(|track| track.has_gid())
+            .map(|track| SpotifyId::from_raw(track.get_gid()))
+            .collect::<Vec<_>>();
 
         let covers = msg.get_cover_group()
-                        .get_image()
-                        .iter()
-                        .filter(|image| image.has_file_id())
-                        .map(|image| {
-                            let mut dst = [0u8; 20];
-                            dst.clone_from_slice(image.get_file_id());
-                            FileId(dst)
-                        })
-                        .collect::<Vec<_>>();
+            .get_image()
+            .iter()
+            .filter(|image| image.has_file_id())
+            .map(|image| {
+                let mut dst = [0u8; 20];
+                dst.clone_from_slice(image.get_file_id());
+                FileId(dst)
+            })
+            .collect::<Vec<_>>();
 
         Album {
             id: SpotifyId::from_raw(msg.get_gid()),
@@ -185,7 +184,6 @@ impl Metadata for Album {
     }
 }
 
-
 impl Metadata for Artist {
     type Message = protocol::metadata::Artist;
 
@@ -197,23 +195,48 @@ impl Metadata for Artist {
         let country = session.country();
 
         let top_tracks: Vec<SpotifyId> = match msg.get_top_track()
-                            .iter()
-                            .find(|tt| !tt.has_country() || countrylist_contains(tt.get_country(), &country)) {
-                                Some(tracks) => {
-                                    tracks.get_track()
-                                    .iter()
-                                    .filter(|track| track.has_gid())
-                                    .map(|track| SpotifyId::from_raw(track.get_gid()))
-                                    .collect::<Vec<_>>()
-                                },
-                                None => Vec::new()
-                            };
-
+            .iter()
+            .find(|tt| !tt.has_country() || countrylist_contains(tt.get_country(), &country))
+        {
+            Some(tracks) => tracks
+                .get_track()
+                .iter()
+                .filter(|track| track.has_gid())
+                .map(|track| SpotifyId::from_raw(track.get_gid()))
+                .collect::<Vec<_>>(),
+            None => Vec::new(),
+        };
 
         Artist {
             id: SpotifyId::from_raw(msg.get_gid()),
             name: msg.get_name().to_owned(),
-            top_tracks: top_tracks
+            top_tracks: top_tracks,
+        }
+    }
+}
+
+struct StrChunks<'s>(&'s str, usize);
+
+trait StrChunksExt {
+    fn chunks(&self, size: usize) -> StrChunks;
+}
+
+impl StrChunksExt for str {
+    fn chunks(&self, size: usize) -> StrChunks {
+        StrChunks(self, size)
+    }
+}
+
+impl<'s> Iterator for StrChunks<'s> {
+    type Item = &'s str;
+    fn next(&mut self) -> Option<&'s str> {
+        let &mut StrChunks(data, size) = self;
+        if data.is_empty() {
+            None
+        } else {
+            let ret = Some(&data[..size]);
+            self.0 = &data[size..];
+            ret
         }
     }
 }
diff --git a/metadata/src/metadata.rs b/metadata/src/metadata.rs
deleted file mode 100644
index e69de29b..00000000
diff --git a/playback/src/player.rs b/playback/src/player.rs
index 48f7f307..e5497365 100644
--- a/playback/src/player.rs
+++ b/playback/src/player.rs
@@ -11,7 +11,7 @@ use std::time::Duration;
 
 use config::{Bitrate, PlayerConfig};
 use core::session::Session;
-use core::util::SpotifyId;
+use core::spotify_id::SpotifyId;
 
 use audio_backend::Sink;
 use audio::{AudioFile, AudioDecrypt};