diff --git a/lib/lang/opaque.go b/lib/lang/opaque.go
index 2084baa8ed3f..265946a171eb 100644
--- a/lib/lang/opaque.go
+++ b/lib/lang/opaque.go
@@ -1,9 +1,6 @@
 package lang
 
 import (
-	"unicode"
-	"unicode/utf8"
-
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"golang.org/x/exp/maps"
@@ -27,8 +24,8 @@ func ignoreUnexportedAlways() cmp.Option {
 			if !ok {
 				return false
 			}
-			r, _ := utf8.DecodeRuneInString(sf.Name())
-			return !unicode.IsUpper(r)
+			c := sf.Name()[0]
+			return c < 'A' || c > 'Z'
 		},
 		cmpOptIgnore,
 	)