diff --git a/system/libraries/Session.php b/system/libraries/Session.php
index 4e5e256..af38dc3 100644
--- a/system/libraries/Session.php
+++ b/system/libraries/Session.php
@@ -155,12 +155,6 @@
 	 */
 	public $time_reference			= 'local';
 
-	/**
-	 * Probablity level of garbage collection of old sessions
-	 *
-	 * @var int
-	 */
-	public $gc_probability			= 5;
 
 	/**
 	 * Session data
@@ -201,7 +195,7 @@
 
 		// Set all the session preferences, which can either be set
 		// manually via the $params array above or via the config file
-		foreach (array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name', 'sess_expiration', 'sess_expire_on_close', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name', 'cookie_path', 'cookie_domain', 'cookie_secure', 'cookie_httponly', 'sess_time_to_update', 'time_reference', 'cookie_prefix', 'encryption_key', 'gc_probability') as $key)
+		foreach (array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name', 'sess_expiration', 'sess_expire_on_close', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name', 'cookie_path', 'cookie_domain', 'cookie_secure', 'cookie_httponly', 'sess_time_to_update', 'time_reference', 'cookie_prefix', 'encryption_key') as $key)
 		{
 			$this->$key = isset($params[$key]) ? $params[$key] : $this->CI->config->item($key);
 		}
@@ -940,8 +934,11 @@
 			return;
 		}
 
+		$probability = ini_get('session.gc_probability');
+		$divisor = ini_get('session.gc_divisor');
+
 		srand(time());
-		if ((rand() % 100) < $this->gc_probability)
+		if ((mt_rand(0, $divisor) / $divisor) < $probability)
 		{
 			$expire = $this->now - $this->sess_expiration;