1 files changed, 2 insertions, 0 deletions
diff --git a/synapse/rest/client/v1/register.py b/synapse/rest/client/v1/register.py
index 25d63a0b0b..83872f5f60 100644
--- a/synapse/rest/client/v1/register.py
+++ b/synapse/rest/client/v1/register.py
@@ -336,7 +336,9 @@ class RegisterRestServlet(ClientV1RestServlet):
             digestmod=sha1,
         )
         want_mac.update(user)
+        want_mac.update("\x00")
         want_mac.update(password)
+        want_mac.update("\x00")
         want_mac.update("admin" if admin else "notadmin")
         want_mac = want_mac.hexdigest()