diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 2813222619..5b98940292 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -36,7 +36,7 @@ REQUIREMENTS = {
     "blist": ["blist"],
     "pysaml2>=3.0.0,<4.0.0": ["saml2>=3.0.0,<4.0.0"],
     "pymacaroons-pynacl": ["pymacaroons"],
-    "msgpack-python": ["msgpack"],
+    "cbor2": ["cbor2"],
 }
 CONDITIONAL_REQUIREMENTS = {
     "web_client": {
diff --git a/synapse/types.py b/synapse/types.py
index 0f787d3a43..2bbc7ae3b7 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -18,7 +18,7 @@ from synapse.api.errors import SynapseError
 from collections import namedtuple
 
 from unpaddedbase64 import encode_base64, decode_base64
-import ujson as serializer
+import cbor2 as serializer
 
 
 Requester = namedtuple("Requester", ["user", "access_token_id", "is_guest"])