diff --git a/specification/appendices/threat_model.rst b/specification/appendices/threat_model.rst
index 0dea62e0..a25b9879 100644
--- a/specification/appendices/threat_model.rst
+++ b/specification/appendices/threat_model.rst
@@ -134,7 +134,7 @@ An attacker could try to convince servers within a chatroom to send messages to
 a server it controls that was not authorised to be within the chatroom.
 
 Threat: Disclosure to Servers Within Chatroom
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
++++++++++++++++++++++++++++++++++++++++++++++
 
 An attacker could take control of a server within a chatroom to expose message
 contents or metadata for messages in that room.