diff --git a/spacy/en/__init__.py b/spacy/en/__init__.py
index d368aa05d..4eccb1d37 100644
--- a/spacy/en/__init__.py
+++ b/spacy/en/__init__.py
@@ -80,11 +80,16 @@ class English(object):
     ):
         
         self.data_dir = data_dir
+
+        if path.exists(path.join(data_dir, 'vocab', 'oov_prob')):
+            oov_prob = float(open(path.join(data_dir, 'vocab', 'oov_prob')).read())
+        else:
+            oov_prob = None
         
         self.vocab = Vocab(data_dir=path.join(data_dir, 'vocab') if data_dir else None,
                            get_lex_props=get_lex_props, load_vectors=load_vectors,
                            pos_tags=POS_TAGS,
-                           oov_prob=float(open(path.join(data_dir, 'vocab', 'oov_prob')).read()))
+                           oov_prob=oov_prob)
         if Tagger is True:
             Tagger = EnPosTagger
         if Parser is True: