diff --git a/spacy/tests/tokens/test_tokens_api.py b/spacy/tests/tokens/test_tokens_api.py
index 04281bd14..47ad8545f 100644
--- a/spacy/tests/tokens/test_tokens_api.py
+++ b/spacy/tests/tokens/test_tokens_api.py
@@ -166,6 +166,7 @@ def test_merge_hang():
 
 def test_sents_empty_string(EN):
     doc = EN(u'')
+    doc.is_parsed = True
     sents = list(doc.sents)
     assert len(sents) == 0