diff --git a/src/Client.php b/src/Client.php
index c8134273..926bc45b 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -51,13 +51,13 @@ class Client
      * @var string
      *      The base URL for authorization requests.
      */
-    const AUTH_URL = 'https://login.microsoftonline.com/common/oauth2/v2.0/authorize';
+    private $auth_url = 'https://login.microsoftonline.com/common/oauth2/v2.0/authorize';
 
     /**
      * @var string
      *      The base URL for token requests.
      */
-    const TOKEN_URL = 'https://login.microsoftonline.com/common/oauth2/v2.0/token';
+    private $token_url = 'https://login.microsoftonline.com/common/oauth2/v2.0/token';
 
     /**
      * @var string
@@ -216,7 +216,7 @@ public function getLogInUrl(array $scopes, $redirectUri, $state = null)
         // redirected to the redirect URI, with a code passed in the query
         // string (the name of the variable is "code"). This is suitable for
         // PHP.
-        return self::AUTH_URL . "?$query";
+        return $this->auth_url . "?$query";
     }
 
     /**
@@ -305,7 +305,7 @@ public function obtainAccessToken($clientSecret, $code)
         ];
 
         $response = $this->httpClient->post(
-            self::TOKEN_URL,
+            $this->token_url,
             ['form_params' => $values]
         );
 
@@ -355,7 +355,7 @@ public function renewAccessToken($clientSecret)
         ];
 
         $response = $this->httpClient->post(
-            self::TOKEN_URL,
+            $this->token_url,
             ['form_params' => $values]
         );
 
@@ -885,4 +885,30 @@ public function getRecent()
             );
         }, $driveItems);
     }
+
+    /**
+     * Sets the auth_url.
+     *
+     *
+     * @since 2.0.0
+     *
+     * @api
+     */
+    public function setAuthUrl($url)
+    {
+        $this->auth_url = $url;
+    }
+
+    /**
+     * Sets the token_url.
+     *
+     *
+     * @since 2.0.0
+     *
+     * @api
+     */
+    public function setTokenUrl($url)
+    {
+        $this->token_url = $url;
+    }
 }