diff --git a/requires/installation.txt b/requires/installation.txt
index 6dfc681..2a8bd43 100644
--- a/requires/installation.txt
+++ b/requires/installation.txt
@@ -1,2 +1,2 @@
-ietfparse>=1.4,<1.5
+ietfparse>=1.5.1,<2
 tornado>=5,<6
diff --git a/sprockets/mixins/mediatype/content.py b/sprockets/mixins/mediatype/content.py
index e3d636c..d865480 100644
--- a/sprockets/mixins/mediatype/content.py
+++ b/sprockets/mixins/mediatype/content.py
@@ -317,6 +317,9 @@ class ContentMixin:
                     acceptable, settings.available_content_types)
                 self._best_response_match = '/'.join(
                     [selected.content_type, selected.content_subtype])
+                if selected.content_suffix is not None:
+                    self._best_response_match = '+'.join(
+                        [self._best_response_match, selected.content_suffix])
             except errors.NoMatch:
                 self._best_response_match = settings.default_content_type
 
@@ -340,6 +343,9 @@ class ContentMixin:
                                          settings.default_content_type))
             content_type = '/'.join([content_type_header.content_type,
                                      content_type_header.content_subtype])
+            if content_type_header.content_suffix is not None:
+                content_type = '+'.join([content_type,
+                                         content_type_header.content_suffix])
             try:
                 handler = settings[content_type]
             except KeyError:
diff --git a/tests.py b/tests.py
index 6f59077..efa1dc2 100644
--- a/tests.py
+++ b/tests.py
@@ -101,6 +101,17 @@ class SendResponseTests(testing.AsyncHTTPTestCase):
         self.assertEqual(response.code, 200)
         self.assertEqual(response.headers['Vary'], 'Accept')
 
+    def test_that_accept_header_with_suffix_is_obeyed(self):
+        content.add_transcoder(
+            self._app,
+            transcoders.MsgPackTranscoder(content_type='expected/content'),
+            'application/vendor+msgpack')
+        response = self.fetch('/', method='POST', body='{}',
+                              headers={'Accept': 'application/vendor+msgpack',
+                                       'Content-Type': 'application/json'})
+        self.assertEqual(response.code, 200)
+        self.assertEqual(response.headers['Content-Type'], 'expected/content')
+
 
 class GetRequestBodyTests(testing.AsyncHTTPTestCase):
 
@@ -135,6 +146,17 @@ class GetRequestBodyTests(testing.AsyncHTTPTestCase):
                   '</param></params></methodCall>').encode('utf-8'))
         self.assertEqual(response.code, 400)
 
+    def test_that_content_type_suffix_is_handled(self):
+        content.add_transcoder(
+            self._app, transcoders.JSONTranscoder(),
+            'application/vendor+json')
+        body = {'hello': 'world'}
+        response = self.fetch(
+            '/', method='POST', body=json.dumps(body),
+            headers={'Content-Type': 'application/vendor+json'})
+        self.assertEqual(response.code, 200)
+        self.assertEqual(json.loads(response.body.decode()), body)
+
 
 class JSONTranscoderTests(unittest.TestCase):