diff --git a/contrib/revsetbenchmarks.py b/contrib/revsetbenchmarks.py
index c8b9c6147108e2e9020ad7034a8632bd11345be5_Y29udHJpYi9yZXZzZXRiZW5jaG1hcmtzLnB5..c04e5e937139f13772e6597c1c070b0feafcc639_Y29udHJpYi9yZXZzZXRiZW5jaG1hcmtzLnB5 100755
--- a/contrib/revsetbenchmarks.py
+++ b/contrib/revsetbenchmarks.py
@@ -22,7 +22,7 @@
     proc = Popen(*args, **kwargs)
     output, error = proc.communicate()
     if proc.returncode != 0:
-        raise CalledProcessError(proc.returncode, ' '.join(args))
+        raise CalledProcessError(proc.returncode, ' '.join(args[0]))
     return output
 
 def update(rev):