1 files changed, 3 insertions, 3 deletions
diff --git a/src/mongo/db/pipeline/builder.cpp b/src/mongo/db/pipeline/builder.cpp
index 8af427d8c9f..a85d75ce02f 100755
--- a/src/mongo/db/pipeline/builder.cpp
+++ b/src/mongo/db/pipeline/builder.cpp
@@ -46,7 +46,7 @@ namespace mongo {
         pBuilder->append(fieldName, d);
     }
 
-    void BuilderObj::append(string s) {
+    void BuilderObj::append(const std::string& s) {
         pBuilder->append(fieldName, s);
     }
 
@@ -71,7 +71,7 @@ namespace mongo {
     }
 
     BuilderObj::BuilderObj(
-        BSONObjBuilder *pObjBuilder, string theFieldName):
+        BSONObjBuilder *pObjBuilder, const std::string& theFieldName):
         pBuilder(pObjBuilder),
         fieldName(theFieldName) {
     }
@@ -101,7 +101,7 @@ namespace mongo {
         pBuilder->append(d);
     }
 
-    void BuilderArray::append(string s) {
+    void BuilderArray::append(const std::string& s) {
         pBuilder->append(s);
     }