diff --git a/scripting/bench.cpp b/scripting/bench.cpp
index 1ac7f04a55e..9ada7d6495c 100644
--- a/scripting/bench.cpp
+++ b/scripting/bench.cpp
@@ -142,7 +142,7 @@ namespace mongo {
                     conn->remove( ns , fixQuery( e["query"].Obj() ) );
                 }
                 else if ( op == "update" ) {
-                    conn->update( ns , fixQuery( e["query"].Obj() ) , e["update"].Obj() );
+                    conn->update( ns , fixQuery( e["query"].Obj() ) , e["update"].Obj() , e["upsert"].trueValue() );
                 }
                 else {
                     log() << "don't understand op: " << op << endl;