1 files changed, 1 insertions, 1 deletions
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp
index 871a81df95a..d4d38a2b2be 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp
@@ -941,7 +941,7 @@ bool DocumentSourceInternalUnpackBucket::optimizeLastpoint(Pipeline::SourceConta
     auto isSortValidForGroup = [&](AccumulatorDocumentsNeeded targetAccum) {
         bool firstpointTimeIsAscending =
             (targetAccum == AccumulatorDocumentsNeeded::kFirstDocument);
-        for (auto entry : sortStage->getSortKeyPattern()) {
+        for (const auto& entry : sortStage->getSortKeyPattern()) {
             auto isTimeField = entry.fieldPath->fullPath() == timeField;
             if (isTimeField && (entry.isAscending == firstpointTimeIsAscending)) {
                 // This is a first-point query, which is disallowed.