diff --git a/changelog.d/5633.bugfix b/changelog.d/5633.bugfix
index c0aef2721d..19aa87147c 100644
--- a/changelog.d/5633.bugfix
+++ b/changelog.d/5633.bugfix
@@ -1 +1 @@
-Fix bad room creation with power_level_content_override.users not containing creator_id.
\ No newline at end of file
+Fix createRoom power_level_content_override behaviour to match the spec
\ No newline at end of file
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 7fe8801d68..db28ee56aa 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -750,7 +750,7 @@ class RoomCreationHandler(BaseHandler):
                     power_level_content["users"][invitee] = 100
 
             if power_level_content_override:
-                power_level_content.update(power_level_content_override)
+                power_level_content = power_level_content_override
 
             if creator_id not in power_level_content["users"]:
                 raise SynapseError(