diff --git a/encode_test.go b/encode_test.go
index c7afadb7..63740f35 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -1022,12 +1022,13 @@ func (u *unmarshalerText) UnmarshalText(b []byte) error {
 }
 
 func TestTextMarshalerMapKeysAreSorted(t *testing.T) {
-	b, err := json.Marshal(map[unmarshalerText]int{
+	data := map[unmarshalerText]int{
 		{"x", "y"}: 1,
 		{"y", "x"}: 2,
 		{"a", "z"}: 3,
 		{"z", "a"}: 4,
-	})
+	}
+	b, err := json.Marshal(data)
 	if err != nil {
 		t.Fatalf("Failed to Marshal text.Marshaler: %v", err)
 	}
@@ -1035,6 +1036,14 @@ func TestTextMarshalerMapKeysAreSorted(t *testing.T) {
 	if string(b) != want {
 		t.Errorf("Marshal map with text.Marshaler keys: got %#q, want %#q", b, want)
 	}
+
+	b, err = stdjson.Marshal(data)
+	if err != nil {
+		t.Fatalf("Failed to std Marshal text.Marshaler: %v", err)
+	}
+	if string(b) != want {
+		t.Errorf("std Marshal map with text.Marshaler keys: got %#q, want %#q", b, want)
+	}
 }
 
 // https://golang.org/issue/33675