diff --git a/util/strutil/quote_test.go b/util/strutil/quote_test.go
index 6fde4ca14..fa34b42ac 100644
--- a/util/strutil/quote_test.go
+++ b/util/strutil/quote_test.go
@@ -87,6 +87,7 @@ var misquoted = []string{
 	`'\9'`,
 	`'\19'`,
 	`'\129'`,
+	`'\400'`,
 	`"\x1!"`,
 	`"\U12345678"`,
 	`"\z"`,