diff --git a/Library/Think/Db/Driver/Sqlsrv.php b/Library/Think/Db/Driver/Sqlsrv.php
index ee95b777..07329ed0 100644
--- a/Library/Think/Db/Driver/Sqlsrv.php
+++ b/Library/Think/Db/Driver/Sqlsrv.php
@@ -11,6 +11,7 @@
 
 namespace Think\Db\Driver;
 use Think\Db\Driver;
+use PDO;
 
 /**
  * Sqlsrv数据库驱动