diff --git a/examples/github.rs b/examples/github.rs
index 39082f0..9b36ca7 100644
--- a/examples/github.rs
+++ b/examples/github.rs
@@ -14,10 +14,11 @@ fn main() {
     let connector = HttpsConnector::new(tls);
     let https = hyper::Client::with_connector(connector);
 
-    let client = Client::<GitHub>::new(
+    let client = Client::new(
+        GitHub,
         String::from("01774654cd9a6051e478"),
         String::from("9f14d16d95d605e715ec1a9aecec220d2565fd5c"),
-        Some(String::from("https://cmcenroe.me/oauth2-paste/"))
+        Some(String::from("https://cmcenroe.me/oauth2-paste/")),
     );
 
     let auth_uri = client.auth_uri(Some("user"), None).unwrap();
diff --git a/examples/google-installed.rs b/examples/google-installed.rs
index 1d4cc17..30909d0 100644
--- a/examples/google-installed.rs
+++ b/examples/google-installed.rs
@@ -14,7 +14,8 @@ fn main() {
     let connector = HttpsConnector::new(tls);
     let https = hyper::Client::with_connector(connector);
 
-    let client = Client::<Installed>::new(
+    let client = Client::new(
+        Installed,
         String::from("143225766783-ip2d9qv6sdr37276t77luk6f7bhd6bj5.apps.googleusercontent.com"),
         String::from("3kZ5WomzHFlN2f_XbhkyPd3o"),
         Some(String::from(REDIRECT_URI_OOB)),
diff --git a/examples/google-web.rs b/examples/google-web.rs
index 2fe8e79..f7070a3 100644
--- a/examples/google-web.rs
+++ b/examples/google-web.rs
@@ -14,7 +14,8 @@ fn main() {
     let connector = HttpsConnector::new(tls);
     let https = hyper::Client::with_connector(connector);
 
-    let client = Client::<Web>::new(
+    let client = Client::new(
+        Web,
         String::from("143225766783-0h4h5ktpvhc7kqp6ohbpd2sssqrap57n.apps.googleusercontent.com"),
         String::from("7Xjn-vRN-8qsz3Zh9zZGkHsM"),
         Some(String::from("https://cmcenroe.me/oauth2-paste/")),
diff --git a/examples/imgur.rs b/examples/imgur.rs
index 864df7d..99042b0 100644
--- a/examples/imgur.rs
+++ b/examples/imgur.rs
@@ -14,7 +14,8 @@ fn main() {
     let connector = HttpsConnector::new(tls);
     let https = hyper::Client::with_connector(connector);
 
-    let client = Client::<Imgur>::new(
+    let client = Client::new(
+        Imgur,
         String::from("505c8ca804230e0"),
         String::from("c898d8cf28404102752b2119a3a1c6aab49899c8"),
         Some(String::from("https://cmcenroe.me/oauth2-paste/"))
diff --git a/src/client/mod.rs b/src/client/mod.rs
index 237019a..5d3f04a 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -17,7 +17,10 @@ use token::{Token, Lifetime, Refresh};
 
 /// OAuth 2.0 client.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Client<P: Provider> {
+pub struct Client<P> {
+    /// OAuth provider.
+    pub provider: P,
+
     /// Client ID.
     pub client_id: String,
 
@@ -26,13 +29,10 @@ pub struct Client<P: Provider> {
 
     /// Redirect URI.
     pub redirect_uri: Option<String>,
-
-    /// The provider.
-    pub provider: P,
 }
 
-impl<P: Provider + Default> Client<P> {
-     /// Creates a client.
+impl<P: Provider> Client<P> {
+    /// Creates a client.
     ///
     /// # Examples
     ///
@@ -40,30 +40,24 @@ impl<P: Provider + Default> Client<P> {
     /// use inth_oauth2::Client;
     /// use inth_oauth2::provider::google::Installed;
     ///
-    /// let client = Client::<Installed>::new(
+    /// let client = Client::new(
+    ///     Installed,
     ///     String::from("CLIENT_ID"),
     ///     String::from("CLIENT_SECRET"),
-    ///     Some(String::from("urn:ietf:wg:oauth:2.0:oob"))
+    ///     Some(String::from("urn:ietf:wg:oauth:2.0:oob")),
     /// );
     /// ```
-    pub fn new(client_id: String, client_secret: String, redirect_uri: Option<String>) -> Self {
-        Client::with_provider(client_id, client_secret,  P::default(), redirect_uri)
-    }
-}
-
-impl<P: Provider> Client<P> {
-    /// Creates a client with a given Provider. Use when the provider needs non-default Initialization.
-    pub fn with_provider(
-            client_id: String, 
-            client_secret: String, 
-            provider: P, 
-            redirect_uri: Option<String>
+    pub fn new(
+        provider: P,
+        client_id: String,
+        client_secret: String,
+        redirect_uri: Option<String>,
     ) -> Self {
         Client {
+            provider,
             client_id,
             client_secret,
             redirect_uri,
-            provider
         }
     }
 
@@ -77,15 +71,16 @@ impl<P: Provider> Client<P> {
     /// use inth_oauth2::Client;
     /// use inth_oauth2::provider::google::Installed;
     ///
-    /// let client = Client::<Installed>::new(
+    /// let client = Client::new(
+    ///     Installed,
     ///     String::from("CLIENT_ID"),
     ///     String::from("CLIENT_SECRET"),
-    ///     Some(String::from("urn:ietf:wg:oauth:2.0:oob"))
+    ///     Some(String::from("urn:ietf:wg:oauth:2.0:oob")),
     /// );
     ///
     /// let auth_uri = client.auth_uri(
     ///     Some("https://www.googleapis.com/auth/userinfo.email"),
-    ///     None
+    ///     None,
     /// );
     /// ```
     pub fn auth_uri(&self, scope: Option<&str>, state: Option<&str>) -> Result<Url, ClientError>
@@ -112,12 +107,12 @@ impl<P: Provider> Client<P> {
         Ok(uri)
     }
 
-    fn post_token<'a>(
-        &'a self,
+    fn post_token(
+        &self,
         http_client: &hyper::Client,
-        mut body: Serializer<String>
+        mut body: Serializer<String>,
     ) -> Result<Value, ClientError> {
-        if P::credentials_in_body() {
+        if self.provider.credentials_in_body() {
             body.append_pair("client_id", &self.client_id);
             body.append_pair("client_secret", &self.client_secret);
         }
@@ -157,7 +152,7 @@ impl<P: Provider> Client<P> {
     pub fn request_token(
         &self,
         http_client: &hyper::Client,
-        code: &str
+        code: &str,
     ) -> Result<P::Token, ClientError> {
         let mut body = Serializer::new(String::new());
         body.append_pair("grant_type", "authorization_code");
@@ -173,7 +168,7 @@ impl<P: Provider> Client<P> {
     }
 }
 
-impl<P: Provider> Client<P> where P::Token: Token<Refresh> {
+impl<P> Client<P> where P: Provider, P::Token: Token<Refresh> {
     /// Refreshes an access token.
     ///
     /// See [RFC 6749, section 6](http://tools.ietf.org/html/rfc6749#section-6).
@@ -181,7 +176,7 @@ impl<P: Provider> Client<P> where P::Token: Token<Refresh> {
         &self,
         http_client: &hyper::Client,
         token: P::Token,
-        scope: Option<&str>
+        scope: Option<&str>,
     ) -> Result<P::Token, ClientError> {
         let mut body = Serializer::new(String::new());
         body.append_pair("grant_type", "refresh_token");
@@ -197,7 +192,11 @@ impl<P: Provider> Client<P> where P::Token: Token<Refresh> {
     }
 
     /// Ensures an access token is valid by refreshing it if necessary.
-    pub fn ensure_token(&self, http_client: &hyper::Client, token: P::Token) -> Result<P::Token, ClientError> {
+    pub fn ensure_token(
+        &self,
+        http_client: &hyper::Client,
+        token: P::Token,
+    ) -> Result<P::Token, ClientError> {
         if token.lifetime().expired() {
             self.refresh_token(http_client, token, None)
         } else {
@@ -212,18 +211,17 @@ mod tests {
     use provider::Provider;
     use super::Client;
 
-    #[derive(Default)]
     struct Test;
     impl Provider for Test {
         type Lifetime = Static;
         type Token = Bearer<Static>;
-        fn auth_uri(&self) -> &'static str { "http://example.com/oauth2/auth" }
-        fn token_uri(&self) -> &'static str { "http://example.com/oauth2/token" }
+        fn auth_uri(&self) -> &str { "http://example.com/oauth2/auth" }
+        fn token_uri(&self) -> &str { "http://example.com/oauth2/token" }
     }
 
     #[test]
     fn auth_uri() {
-        let client = Client::<Test>::new(String::from("foo"), String::from("bar"), None);
+        let client = Client::new(Test, String::from("foo"), String::from("bar"), None);
         assert_eq!(
             "http://example.com/oauth2/auth?response_type=code&client_id=foo",
             client.auth_uri(None, None).unwrap().as_str()
@@ -232,10 +230,11 @@ mod tests {
 
     #[test]
     fn auth_uri_with_redirect_uri() {
-        let client = Client::<Test>::new(
+        let client = Client::new(
+            Test,
             String::from("foo"),
             String::from("bar"),
-            Some(String::from("http://example.com/oauth2/callback"))
+            Some(String::from("http://example.com/oauth2/callback")),
         );
         assert_eq!(
             "http://example.com/oauth2/auth?response_type=code&client_id=foo&redirect_uri=http%3A%2F%2Fexample.com%2Foauth2%2Fcallback",
@@ -245,7 +244,7 @@ mod tests {
 
     #[test]
     fn auth_uri_with_scope() {
-        let client = Client::<Test>::new(String::from("foo"), String::from("bar"), None);
+        let client = Client::new(Test, String::from("foo"), String::from("bar"), None);
         assert_eq!(
             "http://example.com/oauth2/auth?response_type=code&client_id=foo&scope=baz",
             client.auth_uri(Some("baz"), None).unwrap().as_str()
@@ -254,7 +253,7 @@ mod tests {
 
     #[test]
     fn auth_uri_with_state() {
-        let client = Client::<Test>::new(String::from("foo"), String::from("bar"), None);
+        let client = Client::new(Test, String::from("foo"), String::from("bar"), None);
         assert_eq!(
             "http://example.com/oauth2/auth?response_type=code&client_id=foo&state=baz",
             client.auth_uri(None, Some("baz")).unwrap().as_str()
diff --git a/src/lib.rs b/src/lib.rs
index 0de5eb6..7b47169 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -34,10 +34,11 @@
 //! use inth_oauth2::Client;
 //! use inth_oauth2::provider::google::Installed;
 //!
-//! let client = Client::<Installed>::new(
+//! let client = Client::new(
+//!     Installed,
 //!     String::from("client_id"),
 //!     String::from("client_secret"),
-//!     Some(String::from("redirect_uri"))
+//!     Some(String::from("redirect_uri")),
 //! );
 //! ```
 //!
@@ -46,7 +47,7 @@
 //! ```
 //! # use inth_oauth2::Client;
 //! # use inth_oauth2::provider::google::Installed;
-//! # let client = Client::<Installed>::new(String::new(), String::new(), None);
+//! # let client = Client::new(Installed, String::new(), String::new(), None);
 //! let auth_uri = client.auth_uri(Some("scope"), Some("state")).unwrap();
 //! println!("Authorize the application by clicking on the link: {}", auth_uri);
 //! ```
@@ -61,7 +62,7 @@
 //! use inth_oauth2::{Client, Token};
 //! # use inth_oauth2::provider::google::Installed;
 //! # fn main() {
-//! # let client = Client::<Installed>::new(String::new(), String::new(), None);
+//! # let client = Client::new(Installed, String::new(), String::new(), None);
 //!
 //! let mut code = String::new();
 //! io::stdin().read_line(&mut code).unwrap();
@@ -80,7 +81,7 @@
 //! ```no_run
 //! # use inth_oauth2::Client;
 //! # use inth_oauth2::provider::google::Installed;
-//! # let client = Client::<Installed>::new(String::new(), String::new(), None);
+//! # let client = Client::new(Installed, String::new(), String::new(), None);
 //! # let https = Default::default();
 //! # let token = client.request_token(&https, "").unwrap();
 //! let token = client.refresh_token(&https, token, None).unwrap();
@@ -91,7 +92,7 @@
 //! ```no_run
 //! # use inth_oauth2::Client;
 //! # use inth_oauth2::provider::google::Installed;
-//! # let client = Client::<Installed>::new(String::new(), String::new(), None);
+//! # let client = Client::new(Installed, String::new(), String::new(), None);
 //! # let https = Default::default();
 //! # let mut token = client.request_token(&https, "").unwrap();
 //! // Refresh token only if it has expired.
@@ -110,7 +111,7 @@
 //! use hyper::header::Authorization;
 //!
 //! # fn main() {
-//! # let oauth_client = Client::<Installed>::new(String::new(), String::new(), None);
+//! # let oauth_client = Client::new(Installed, String::new(), String::new(), None);
 //! # let https = Default::default();
 //! # let token = oauth_client.request_token(&https, "").unwrap();
 //! let request = https.get("https://example.com/resource")
@@ -129,7 +130,7 @@
 //! # use inth_oauth2::provider::google::Installed;
 //! # fn main() {
 //! # let http_client = Default::default();
-//! # let client = Client::<Installed>::new(String::new(), String::new(), None);
+//! # let client = Client::new(Installed, String::new(), String::new(), None);
 //! # let token = client.request_token(&http_client, "").unwrap();
 //! let json = serde_json::to_string(&token).unwrap();
 //! # }
@@ -144,7 +145,7 @@
     unused_extern_crates,
     unused_import_braces,
     unused_qualifications,
-    variant_size_differences
+    variant_size_differences,
 )]
 
 #[macro_use]
diff --git a/src/provider.rs b/src/provider.rs
index dae2d5b..e7b4cfe 100644
--- a/src/provider.rs
+++ b/src/provider.rs
@@ -13,15 +13,11 @@ pub trait Provider {
     /// The authorization endpoint URI.
     ///
     /// See [RFC 6749, section 3.1](http://tools.ietf.org/html/rfc6749#section-3.1).
-    ///
-    /// Note: likely to become an associated constant.
     fn auth_uri(&self) -> &str;
 
     /// The token endpoint URI.
     ///
     /// See [RFC 6749, section 3.2](http://tools.ietf.org/html/rfc6749#section-3.2).
-    ///
-    /// Note: likely to become an associated constant.
     fn token_uri(&self) -> &str;
 
     /// Provider requires credentials via request body.
@@ -30,9 +26,7 @@ pub trait Provider {
     /// as part of the request body.
     ///
     /// See [RFC 6749, section 2.3.1](http://tools.ietf.org/html/rfc6749#section-2.3.1).
-    ///
-    /// Note: likely to become an associated constant.
-    fn credentials_in_body() -> bool { false }
+    fn credentials_in_body(&self) -> bool { false }
 }
 
 /// Google OAuth 2.0 providers.
@@ -62,49 +56,49 @@ pub mod google {
     ///
     /// See [Using OAuth 2.0 for Web Server
     /// Applications](https://developers.google.com/identity/protocols/OAuth2WebServer).
-    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
+    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
     pub struct Web;
     impl Provider for Web {
         type Lifetime = Expiring;
         type Token = Bearer<Expiring>;
-        fn auth_uri(&self) -> &'static str { "https://accounts.google.com/o/oauth2/v2/auth" }
-        fn token_uri(&self) -> &'static str { "https://www.googleapis.com/oauth2/v4/token" }
+        fn auth_uri(&self) -> &str { "https://accounts.google.com/o/oauth2/v2/auth" }
+        fn token_uri(&self) -> &str { "https://www.googleapis.com/oauth2/v4/token" }
     }
 
     /// Google OAuth 2.0 provider for installed applications.
     ///
     /// See [Using OAuth 2.0 for Installed
     /// Applications](https://developers.google.com/identity/protocols/OAuth2InstalledApp).
-    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
+    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
     pub struct Installed;
     impl Provider for Installed {
         type Lifetime = Refresh;
         type Token = Bearer<Refresh>;
-        fn auth_uri(&self) -> &'static str { "https://accounts.google.com/o/oauth2/v2/auth" }
-        fn token_uri(&self) -> &'static str { "https://www.googleapis.com/oauth2/v4/token" }
+        fn auth_uri(&self) -> &str { "https://accounts.google.com/o/oauth2/v2/auth" }
+        fn token_uri(&self) -> &str { "https://www.googleapis.com/oauth2/v4/token" }
     }
 }
 
 /// GitHub OAuth 2.0 provider.
 ///
 /// See [OAuth, GitHub Developer Guide](https://developer.github.com/v3/oauth/).
-#[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct GitHub;
 impl Provider for GitHub {
     type Lifetime = Static;
     type Token = Bearer<Static>;
-    fn auth_uri(&self) -> &'static str { "https://github.com/login/oauth/authorize" }
-    fn token_uri(&self) -> &'static str { "https://github.com/login/oauth/access_token" }
+    fn auth_uri(&self) -> &str { "https://github.com/login/oauth/authorize" }
+    fn token_uri(&self) -> &str { "https://github.com/login/oauth/access_token" }
 }
 
 /// Imgur OAuth 2.0 provider.
 ///
 /// See [OAuth 2.0, Imgur](https://api.imgur.com/oauth2).
-#[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Imgur;
 impl Provider for Imgur {
     type Lifetime = Refresh;
     type Token = Bearer<Refresh>;
-    fn auth_uri(&self) -> &'static str { "https://api.imgur.com/oauth2/authorize" }
-    fn token_uri(&self) -> &'static str { "https://api.imgur.com/oauth2/token" }
+    fn auth_uri(&self) -> &str { "https://api.imgur.com/oauth2/authorize" }
+    fn token_uri(&self) -> &str { "https://api.imgur.com/oauth2/token" }
 }
diff --git a/tests/auth_uri.rs b/tests/auth_uri.rs
index f67e053..8035e30 100644
--- a/tests/auth_uri.rs
+++ b/tests/auth_uri.rs
@@ -19,7 +19,8 @@ fn assert_get_uri_ok(uri: Url) {
 
 #[test]
 fn google_web_auth_uri_ok() {
-    let client = Client::<google::Web>::new(
+    let client = Client::new(
+        google::Web,
         String::from("143225766783-0h4h5ktpvhc7kqp6ohbpd2sssqrap57n.apps.googleusercontent.com"),
         String::new(),
         Some(String::from("https://cmcenroe.me/oauth2-paste/")),
@@ -33,24 +34,26 @@ fn google_web_auth_uri_ok() {
 
 #[test]
 fn google_installed_auth_uri_ok() {
-    let client = Client::<google::Installed>::new(
+    let client = Client::new(
+        google::Installed,
         String::from("143225766783-ip2d9qv6sdr37276t77luk6f7bhd6bj5.apps.googleusercontent.com"),
         String::new(),
-        Some(String::from("urn:ietf:wg:oauth:2.0:oob"))
+        Some(String::from("urn:ietf:wg:oauth:2.0:oob")),
     );
     let auth_uri = client.auth_uri(
         Some("https://www.googleapis.com/auth/userinfo.email"),
-        Some("state")
+        Some("state"),
     ).unwrap();
     assert_get_uri_ok(auth_uri);
 }
 
 #[test]
 fn github_auth_uri_ok() {
-    let client = Client::<GitHub>::new(
+    let client = Client::new(
+        GitHub,
         String::from("01774654cd9a6051e478"),
         String::new(),
-        Some(String::from("https://cmcenroe.me/oauth2-paste/"))
+        Some(String::from("https://cmcenroe.me/oauth2-paste/")),
     );
     let auth_uri = client.auth_uri(Some("user"), Some("state")).unwrap();
     assert_get_uri_ok(auth_uri);
@@ -58,10 +61,11 @@ fn github_auth_uri_ok() {
 
 #[test]
 fn imgur_auth_uri_ok() {
-    let client = Client::<Imgur>::new(
+    let client = Client::new(
+        Imgur,
         String::from("505c8ca804230e0"),
         String::new(),
-        Some(String::from("https://cmcenroe.me/oauth2-paste/"))
+        Some(String::from("https://cmcenroe.me/oauth2-paste/")),
     );
     let auth_uri = client.auth_uri(None, Some("state")).unwrap();
     assert_get_uri_ok(auth_uri);
diff --git a/tests/mock.rs b/tests/mock.rs
index ce21afc..874a955 100644
--- a/tests/mock.rs
+++ b/tests/mock.rs
@@ -12,31 +12,28 @@ mod provider {
     use inth_oauth2::token::{Bearer, Static, Expiring, Refresh};
     use inth_oauth2::provider::Provider;
 
-    #[derive(Default)]
     pub struct BearerStatic;
     impl Provider for BearerStatic {
         type Lifetime = Static;
         type Token = Bearer<Static>;
-        fn auth_uri(&self) -> &'static str { "https://example.com/oauth/auth" }
-        fn token_uri(&self) -> &'static str { "https://example.com/oauth/token" }
+        fn auth_uri(&self) -> &str { "https://example.com/oauth/auth" }
+        fn token_uri(&self) -> &str { "https://example.com/oauth/token" }
     }
 
-    #[derive(Default)]
     pub struct BearerExpiring;
     impl Provider for BearerExpiring {
         type Lifetime = Expiring;
         type Token = Bearer<Expiring>;
-        fn auth_uri(&self) -> &'static str { "https://example.com/oauth/auth" }
-        fn token_uri(&self) -> &'static str { "https://example.com/oauth/token" }
+        fn auth_uri(&self) -> &str { "https://example.com/oauth/auth" }
+        fn token_uri(&self) -> &str { "https://example.com/oauth/token" }
     }
 
-    #[derive(Default)]
     pub struct BearerRefresh;
     impl Provider for BearerRefresh {
         type Lifetime = Refresh;
         type Token = Bearer<Refresh>;
-        fn auth_uri(&self) -> &'static str { "https://example.com/oauth/auth" }
-        fn token_uri(&self) -> &'static str { "https://example.com/oauth/token" }
+        fn auth_uri(&self) -> &str { "https://example.com/oauth/auth" }
+        fn token_uri(&self) -> &str { "https://example.com/oauth/token" }
     }
 }
 
@@ -72,11 +69,12 @@ mod connector {
 }
 
 macro_rules! mock_client {
-    ($p:ty, $c:ty) => {
-        (Client::<$p>::new(
+    ($p:path, $c:ty) => {
+        (Client::new(
+            $p,
             String::from("client_id"),
             String::from("client_secret"),
-            None
+            None,
         ),
         hyper::Client::with_connector(<$c>::default()))
     }