diff --git a/utilities/document/document_db.cc b/utilities/document/document_db.cc
index 901e91163..b19618533 100644
--- a/utilities/document/document_db.cc
+++ b/utilities/document/document_db.cc
@@ -407,7 +407,6 @@ class SimpleSortedIndex : public Index {
     assert(interval != nullptr);  // because index is useful
     Direction direction;
 
-    std::string op;
     const JSONDocument* limit;
     if (interval->lower_bound != nullptr) {
       limit = interval->lower_bound;