diff --git a/paddle/gserver/tests/LayerGradUtil.h b/paddle/gserver/tests/LayerGradUtil.h
index a35edd2b5e21a500f6b4562f87c667d754f65aaf..88e831f78bd165f63806df6c081d84411be51502 100644
--- a/paddle/gserver/tests/LayerGradUtil.h
+++ b/paddle/gserver/tests/LayerGradUtil.h
@@ -98,9 +98,9 @@ struct InputDef {
 
   InputDef(InputType type,
            string nameIn,
-           std::vector<int> ids,
-           std::vector<int> selfDefinedSeqStartPos = {},
-           std::vector<int> selfDefinedSubSeqStartPos = {})
+           const std::vector<int>& ids,
+           const std::vector<int>& selfDefinedSeqStartPos = {},
+           const std::vector<int>& selfDefinedSubSeqStartPos = {})
       : labelSeqStartPositions(selfDefinedSeqStartPos),
         labelSubSeqStartPositions(selfDefinedSubSeqStartPos),
         ids(ids) {