diff --git a/db/db_impl/db_impl_compaction_flush.cc b/db/db_impl/db_impl_compaction_flush.cc
index a5c57eeb2..f9e578738 100644
--- a/db/db_impl/db_impl_compaction_flush.cc
+++ b/db/db_impl/db_impl_compaction_flush.cc
@@ -1037,7 +1037,7 @@ Status DBImpl::CompactFilesImpl(
   }
 
   if (output_file_names != nullptr) {
-    for (const auto newf : c->edit()->GetNewFiles()) {
+    for (const auto& newf : c->edit()->GetNewFiles()) {
       (*output_file_names)
           .push_back(TableFileName(c->immutable_cf_options()->cf_paths,
                                    newf.second.fd.GetNumber(),
@@ -1137,7 +1137,7 @@ void DBImpl::NotifyOnCompactionBegin(ColumnFamilyData* cfd, Compaction* c,
         }
       }
     }
-    for (const auto newf : c->edit()->GetNewFiles()) {
+    for (const auto& newf : c->edit()->GetNewFiles()) {
       const FileMetaData& meta = newf.second;
       const FileDescriptor& desc = meta.fd;
       const uint64_t file_number = desc.GetNumber();