diff --git a/seafobj/backends/alioss.py b/seafobj/backends/alioss.py
index 94d9283..4d60054 100644
--- a/seafobj/backends/alioss.py
+++ b/seafobj/backends/alioss.py
@@ -21,8 +21,8 @@ def __init__(self, conf):
     def read_object_content(self, obj_id):
         res = self.oss.get_object(self.conf.bucket_name, obj_id)
         if res.status != httplib.OK:
-            raise GetObjectError("Failed to get object %s from bucket %s: %s %s",
-                                 obj_id, self.conf.bucket_name, res.status, res.reason)
+            raise GetObjectError("Failed to get object %s from bucket %s: %s %s" % (
+                                 obj_id, self.conf.bucket_name, res.status, res.reason))
         return res.read()
 
 class SeafObjStoreOSS(AbstractObjStore):