Re-added if ! empty  clause
diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index c5940dd..8516cc6 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -121,7 +121,10 @@
 
 			// End dsn with a semicolon for extra backward compability
 			// if database property was not empty.
-			$this->dsn .= rtrim($this->hostname, ';').';';
+			if( ! empty($this->database))
+			{
+				$this->dsn .= rtrim($this->hostname, ';').';';
+			}
 		}
 		else
 		{