diff --git a/spacy/en/pos.pyx b/spacy/en/pos.pyx
index f882e3f28..fd6d468a9 100644
--- a/spacy/en/pos.pyx
+++ b/spacy/en/pos.pyx
@@ -274,9 +274,11 @@ cdef class EnPosTagger:
                 scores = self.model.score(context)
                 tokens.data[i].tag = arg_max(scores, self.model.n_classes)
                 self.set_morph(i, tokens.data)
+
+        # TODO: Clean this up.
         tokens._tag_strings = tuple(self.tag_names)
-        assert tokens._tag_strings, self.tag_names
         tokens.is_tagged = True
+        tokens._py_tokens = [None] * tokens.length
 
     def train(self, Tokens tokens, object gold_tag_strs):
         cdef int i
diff --git a/spacy/syntax/parser.pyx b/spacy/syntax/parser.pyx
index 0f96e46d9..33e4af179 100644
--- a/spacy/syntax/parser.pyx
+++ b/spacy/syntax/parser.pyx
@@ -87,6 +87,8 @@ cdef class GreedyParser:
             dep_strings[id_] = label
         tokens._dep_strings = tuple(dep_strings)
         tokens.is_parsed = True
+        # TODO: Clean this up.
+        tokens._py_tokens = [None] * tokens.length
         return 0
 
     def train_sent(self, Tokens tokens, list gold_heads, list gold_labels,