diff --git a/tests/bench/utils.js b/tests/bench/utils.js
index f4c8afb4..e1353025 100644
--- a/tests/bench/utils.js
+++ b/tests/bench/utils.js
@@ -1,3 +1,5 @@
+// @ts-check
+
 const DEFAULT_RUNS = 1000;
 const DEFAULT_WARMUPS = 50;