diff --git a/test/benchmark/test-benchmark-http.js b/test/benchmark/test-benchmark-http.js
index 65165c41135301..55a8b29381f5b3 100644
--- a/test/benchmark/test-benchmark-http.js
+++ b/test/benchmark/test-benchmark-http.js
@@ -22,6 +22,7 @@ runBenchmark('http',
                'chunks=0',
                'dur=0.1',
                'duplicates=1',
+               'headerDuplicates=1',
                'input=keep-alive',
                'key=""',
                'len=1',