diff --git a/runutil/sequence.go b/runutil/sequence.go
index c68010f..9bf28d9 100644
--- a/runutil/sequence.go
+++ b/runutil/sequence.go
@@ -833,7 +833,7 @@
 	err := s.r.call(func() error {
 		return ioutil.WriteFile(filename, data, perm)
 	}, fmt.Sprintf("write %q", filename))
-	s.setError(err, fmt.Sprintf("WriteFile(%s, %10s,  %s)", filename, data, perm))
+	s.setError(err, fmt.Sprintf("WriteFile(%s, %.10s,  %s)", filename, data, perm))
 	return s
 }