diff --git a/spacy/syntax/nn_parser.pyx b/spacy/syntax/nn_parser.pyx
index 5449dbbfb..25cab43f8 100644
--- a/spacy/syntax/nn_parser.pyx
+++ b/spacy/syntax/nn_parser.pyx
@@ -531,7 +531,7 @@ cdef class Parser:
     
     def to_disk(self, path, **exclude):
         serializers = {
-            'model': lambda p: self.model.to_disk(p),
+            'model': lambda p: (self.model.to_disk(p) if self.model is not True else True),
             'vocab': lambda p: self.vocab.to_disk(p),
             'moves': lambda p: self.moves.to_disk(p, strings=False),
             'cfg': lambda p: p.open('w').write(json_dumps(self.cfg))
@@ -560,7 +560,7 @@ cdef class Parser:
 
     def to_bytes(self, **exclude):
         serializers = OrderedDict((
-            ('model', lambda: self.model.to_bytes()),
+            ('model', lambda: (self.model.to_bytes() if self.model is not True else True)),
             ('vocab', lambda: self.vocab.to_bytes()),
             ('moves', lambda: self.moves.to_bytes(strings=False)),
             ('cfg', lambda: json.dumps(self.cfg, indent=2, sort_keys=True))