diff --git a/Sources/OAuth2Swift.swift b/Sources/OAuth2Swift.swift
index 2a666284..c422b226 100644
--- a/Sources/OAuth2Swift.swift
+++ b/Sources/OAuth2Swift.swift
@@ -34,18 +34,9 @@ open class OAuth2Swift: OAuthSwift {
     var codeVerifier: String?
 
     // MARK: init
-    public convenience init(consumerKey: String, consumerSecret: String, authorizeUrl: URLConvertible, accessTokenUrl: URLConvertible, responseType: String) {
-        self.init(consumerKey: consumerKey, consumerSecret: consumerSecret, authorizeUrl: authorizeUrl, responseType: responseType)
-        self.accessTokenUrl = accessTokenUrl.string
-    }
-
-    public convenience init(consumerKey: String, consumerSecret: String, authorizeUrl: URLConvertible, accessTokenUrl: URLConvertible, responseType: String, contentType: String) {
-        self.init(consumerKey: consumerKey, consumerSecret: consumerSecret, authorizeUrl: authorizeUrl, responseType: responseType)
-        self.accessTokenUrl = accessTokenUrl.string
+    public init(consumerKey: String, consumerSecret: String, authorizeUrl: URLConvertible, accessTokenUrl: URLConvertible? = nil, responseType: String, contentType: String? = nil) {
+        self.accessTokenUrl = accessTokenUrl?.string
         self.contentType = contentType
-    }
-
-    public init(consumerKey: String, consumerSecret: String, authorizeUrl: URLConvertible, responseType: String) {
         self.consumerKey = consumerKey
         self.consumerSecret = consumerSecret
         self.authorizeUrl = authorizeUrl.string