Use const operator<.

1 files changed, 1 insertions, 1 deletions

diff --git a/searchlib/src/tests/memoryindex/field_index_remover/field_index_remover_test.cpp b/searchlib/src/tests/memoryindex/field_index_remover/field_index_remover_test.cpp
index c0e8871b80a..f11df42f6b1 100644
--- a/searchlib/src/tests/memoryindex/field_index_remover/field_index_remover_test.cpp
+++ b/searchlib/src/tests/memoryindex/field_index_remover/field_index_remover_test.cpp
@@ -19,7 +19,7 @@ struct WordFieldPair {
     WordFieldPair(vespalib::stringref word, uint32_t fieldId)
         : _word(word), _fieldId(fieldId)
     {}
-    bool operator<(const WordFieldPair &rhs) {
+    bool operator<(const WordFieldPair &rhs) const {
         if (_word != rhs._word) {
             return _word < rhs._word;
         }