diff --git a/bson/decoder_test.go b/bson/decoder_test.go
index 4cebea9d0e..7b91590666 100644
--- a/bson/decoder_test.go
+++ b/bson/decoder_test.go
@@ -647,7 +647,8 @@ func TestDecoderConfiguration(t *testing.T) {
 
 		var got objectIDTest
 		err := dec.Decode(&got)
-		assert.EqualError(t, err, "error decoding key id: decoding an object ID to a non-hexadecimal string representation is not supported")
+		const want = "error decoding key id: decoding an object ID into a plain string is not supported (set Decoder.ObjectIDAsHexString to enable decoding as a hexadecimal representation)"
+		assert.EqualError(t, err, want)
 	})
 	t.Run("DefaultDocumentM top-level", func(t *testing.T) {
 		t.Parallel()