diff --git a/scripts/tests b/scripts/tests
index 856737248..a91568689 100755
--- a/scripts/tests
+++ b/scripts/tests
@@ -316,7 +316,7 @@ def bench(force_qemu, verbose, cycles, cpu):
         process_bench,
         force_qemu,
         verbose,
-        [f"CYCLES={cycles}", f"CFLAGS=-mcpu={cpu}"],
+        [f"CYCLES={cycles}", *(f"CFLAGS=-mcpu={cpu}" if cpu is not None else "")],
     )