diff --git a/spacy/tests/vocab_vectors/test_lexeme.py b/spacy/tests/vocab_vectors/test_lexeme.py
index 4288f427c..4eeff5175 100644
--- a/spacy/tests/vocab_vectors/test_lexeme.py
+++ b/spacy/tests/vocab_vectors/test_lexeme.py
@@ -55,7 +55,7 @@ def test_vocab_lexeme_add_flag_provided_id(en_vocab):
     assert en_vocab["199"].check_flag(IS_DIGIT) is False
     assert en_vocab["the"].check_flag(is_len4) is False
     assert en_vocab["dogs"].check_flag(is_len4) is True
-
+    en_vocab.add_flag(lambda string: string.isdigit(), flag_id=IS_DIGIT)
 
 def test_vocab_lexeme_oov_rank(en_vocab):
     """Test that default rank is OOV_RANK."""