diff --git a/spacy/syntax/nn_parser.pyx b/spacy/syntax/nn_parser.pyx
index 82f4e82f3..3e7664bdb 100644
--- a/spacy/syntax/nn_parser.pyx
+++ b/spacy/syntax/nn_parser.pyx
@@ -635,9 +635,9 @@ cdef class Parser:
     def to_disk(self, path, **exclude):
         serializers = {
             'lower_model': lambda p: p.open('wb').write(
-                util.model_to_bytes(self.model[0])),
+                self.model[0].to_bytes()),
             'upper_model': lambda p: p.open('wb').write(
-                util.model_to_bytes(self.model[1])),
+                self.model[1].to_bytes()),
             '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))
@@ -669,8 +669,8 @@ cdef class Parser:
 
     def to_bytes(self, **exclude):
         serializers = {
-            'lower_model': lambda: util.model_to_bytes(self.model[0]),
-            'upper_model': lambda: util.model_to_bytes(self.model[1]),
+            'lower_model': lambda: self.model[0].to_bytes(),
+            'upper_model': lambda: self.model[1].to_bytes(),
             'vocab': lambda: self.vocab.to_bytes(),
             'moves': lambda: self.moves.to_bytes(strings=False),
             'cfg': lambda: ujson.dumps(self.cfg)
@@ -692,7 +692,7 @@ cdef class Parser:
             else:
                 cfg = {}
             self.model[0].from_bytes(msg['lower_model'])
-            util.model[1].from_bytes(msg['upper_model'])
+            self.model[1].from_bytes(msg['upper_model'])
             self.cfg.update(cfg)
         return self
 
diff --git a/spacy/tests/test_misc.py b/spacy/tests/test_misc.py
index 00ee1a93a..80b859c70 100644
--- a/spacy/tests/test_misc.py
+++ b/spacy/tests/test_misc.py
@@ -2,7 +2,6 @@
 from __future__ import unicode_literals
 
 from ..util import ensure_path
-from ..util import model_to_bytes, model_from_bytes
 from .. import util
 from ..displacy import parse_deps, parse_ents
 from ..tokens import Span
@@ -20,41 +19,6 @@ def test_util_ensure_path_succeeds(text):
     assert isinstance(path, Path)
 
 
-@pytest.mark.models
-def test_simple_model_roundtrip_bytes():
-    model = Maxout(5, 10, pieces=2)
-    model.b += 1
-    data = model_to_bytes(model)
-    model.b -= 1
-    model_from_bytes(model, data)
-    assert model.b[0, 0] == 1
-
-
-@pytest.mark.models
-def test_multi_model_roundtrip_bytes():
-    model = chain(Maxout(5, 10, pieces=2), Maxout(2, 3))
-    model._layers[0].b += 1
-    model._layers[1].b += 2
-    data = model_to_bytes(model)
-    model._layers[0].b -= 1
-    model._layers[1].b -= 2
-    model_from_bytes(model, data)
-    assert model._layers[0].b[0, 0] == 1
-    assert model._layers[1].b[0, 0] == 2
-
-
-@pytest.mark.models
-def test_multi_model_load_missing_dims():
-    model = chain(Maxout(5, 10, pieces=2), Maxout(2, 3))
-    model._layers[0].b += 1
-    model._layers[1].b += 2
-    data = model_to_bytes(model)
-
-    model2 = chain(Maxout(5), Maxout())
-    model_from_bytes(model2, data)
-    assert model2._layers[0].b[0, 0] == 1
-    assert model2._layers[1].b[0, 0] == 2
-
 @pytest.mark.parametrize('package', ['numpy'])
 def test_util_is_package(package):
     """Test that an installed package via pip is recognised by util.is_package."""