1 files changed, 4 insertions, 6 deletions
diff --git a/synapse/types.py b/synapse/types.py
index 9666f9d73f..445bdcb4d7 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -56,10 +56,10 @@ def create_requester(user_id, access_token_id=None, is_guest=False,
 
 
 def get_domain_from_id(string):
-    try:
-        return string.split(":", 1)[1]
-    except IndexError:
+    idx = string.find(":")
+    if idx == -1:
         raise SynapseError(400, "Invalid ID: %r" % (string,))
+    return string[idx + 1:]
 
 
 class DomainSpecificString(
@@ -216,9 +216,7 @@ class StreamToken(
             return self
 
     def copy_and_replace(self, key, new_value):
-        d = self._asdict()
-        d[key] = new_value
-        return StreamToken(**d)
+        return self._replace(**{key: new_value})
 
 
 StreamToken.START = StreamToken(