diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 926f65cc8f854e23794779758ecd45a894747236..529d95a8884552e4ed1851f83e213d288f49f606 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -699,7 +699,7 @@ func ToValidUTF8(s, replacement []byte) []byte {
 		if c < utf8.RuneSelf {
 			i++
 			invalid = false
-			b = append(b, byte(c))
+			b = append(b, c)
 			continue
 		}
 		_, wid := utf8.DecodeRune(s[i:])