diff --git a/benchmark/benchmark.py b/benchmark/benchmark.py
index 53441badc..ec0871a2a 100755
--- a/benchmark/benchmark.py
+++ b/benchmark/benchmark.py
@@ -63,6 +63,10 @@ def main(
     if len(dirname.parts) == 1:
         dirname = BENCHMARK_DNAME / dirname
 
+    if clean and not dirname.exists():
+        print(f"--clean requires that {dirname} exists")
+        return
+
     now = datetime.datetime.now()
     now = now.strftime("%Y-%m-%d-%H-%M--")