diff --git a/spacy/pipeline/textcat.py b/spacy/pipeline/textcat.py
index 639ce5514..bc16e790f 100644
--- a/spacy/pipeline/textcat.py
+++ b/spacy/pipeline/textcat.py
@@ -355,7 +355,7 @@ class TextCategorizer(Pipe):
             for cat in y.cats:
                 self.add_label(cat)
         self.require_labels()
-        docs = [Doc(Vocab(), words=["hello"])]
+        docs = [Doc(self.vocab, words=["hello"])]
         truths, _ = self._examples_to_truth(examples)
         self.set_output(len(self.labels))
         self.model.initialize(X=docs, Y=truths)