diff --git a/changelog.d/4033.bugfix b/changelog.d/4033.bugfix
index 8f7a0bbbe..4e9e38cdc 100644
--- a/changelog.d/4033.bugfix
+++ b/changelog.d/4033.bugfix
@@ -1 +1,2 @@
 Synapse now starts on Python 3.7.
+_All_ workers now start on Python 3.
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index fc4b25de1..f5c61dec5 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -68,7 +68,7 @@ class PresenceStatusStubServlet(ClientV1RestServlet):
             "Authorization": auth_headers,
         }
         result = yield self.http_client.get_json(
-            self.main_uri + request.uri,
+            self.main_uri + request.uri.decode('ascii'),
             headers=headers,
         )
         defer.returnValue((200, result))
@@ -125,7 +125,7 @@ class KeyUploadServlet(RestServlet):
                 "Authorization": auth_headers,
             }
             result = yield self.http_client.post_json_get_json(
-                self.main_uri + request.uri,
+                self.main_uri + request.uri.decode('ascii'),
                 body,
                 headers=headers,
             )