diff --git a/src/reprocessing_module/snapshot_reprocessing.cpp b/src/reprocessing_module/snapshot_reprocessing.cpp
index 3071f2d..0648348 100755
--- a/src/reprocessing_module/snapshot_reprocessing.cpp
+++ b/src/reprocessing_module/snapshot_reprocessing.cpp
@@ -30,7 +30,7 @@ static void box_expansion(video_object_info& obj_info, float expand_ratio, int f
 
 void snapshot_reprocessing::screen_effective_snapshot(vector<onelevel_det_result> &vec_det_result){
 
-	for (auto det_result : vec_det_result)
+	for (auto& det_result : vec_det_result)
 	{
 		int effective_count = 0;
 		int effective_idx = 0;