diff --git a/test/fixtures/guess-hash-seed.js b/test/fixtures/guess-hash-seed.js
index c0d072b23d2e48..18a6f5124dc1d8 100644
--- a/test/fixtures/guess-hash-seed.js
+++ b/test/fixtures/guess-hash-seed.js
@@ -134,7 +134,7 @@ const slow_str_gen = (function*() {
   let strgen_i = 0;
   outer:
   while (1) {
-    const str = '#' + (strgen_i++);
+    const str = `#${strgen_i++}`;
     for (let i = 0; i < 1000; i++) {
       if (time_set_lookup(tester_set, str) < tester_set_treshold)
         continue outer;