diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index c6f84e0..c27607e 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -126,7 +126,10 @@
 	 */
 	public function db_connect($persistent = FALSE)
 	{
-		$this->options[PDO::ATTR_PERSISTENT] = $persistent;
+		if ($persistent === TRUE)
+		{
+			$this->options[PDO::ATTR_PERSISTENT] = TRUE;
+		}
 
 		try
 		{
diff --git a/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php b/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
index 84695ee..9a1cbca 100644
--- a/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
+++ b/system/database/drivers/pdo/subdrivers/pdo_dblib_driver.php
@@ -126,7 +126,12 @@
 	 */
 	public function db_connect($persistent = FALSE)
 	{
-		$this->conn_id = parent::db_connect($persistent);
+		if ($persistent === TRUE)
+		{
+			log_message('debug', "dblib driver doesn't support persistent connections");
+		}
+
+		$this->conn_id = parent::db_connect(FALSE);
 
 		if ( ! is_object($this->conn_id))
 		{