diff --git a/spacy/_ml.py b/spacy/_ml.py
index 2d366af74..7a76405fb 100644
--- a/spacy/_ml.py
+++ b/spacy/_ml.py
@@ -438,7 +438,7 @@ def build_tagger_model(nr_class, **cfg):
         token_vector_width = cfg['token_vector_width']
     else:
         token_vector_width = util.env_opt('token_vector_width', 128)
-    pretrained_vectors = cfg['pretrained_vectors']
+    pretrained_vectors = cfg.get('pretrained_vectors')
     with Model.define_operators({'>>': chain, '+': add}):
         if 'tok2vec' in cfg:
             tok2vec = cfg['tok2vec']