diff --git a/spacy/pipeline.pyx b/spacy/pipeline.pyx
index fe50b4cdd..0c58a378a 100644
--- a/spacy/pipeline.pyx
+++ b/spacy/pipeline.pyx
@@ -521,7 +521,7 @@ class Tagger(Pipe):
         if values is None:
             values = {POS: "X"}
         tag_map[label] = values
-        morph_feats = Morphology._morph2features
+        morph_feats = self.vocab.morphology._morph2features
         self.vocab.morphology = Morphology(
             self.vocab.strings, tag_map=tag_map,
             lemmatizer=self.vocab.morphology.lemmatizer,