diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index c0036e1f40ffdfce2e8c4e75c43a933d14f0c4e1..7b68585a1722a5faf7ce0a8c689d588939ee1b22 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -82,7 +82,7 @@ class RegistrationHandler(BaseHandler):
         yield run_on_reactor()
         password_hash = None
         if password:
-            password_hash = bcrypt.hashpw(password, bcrypt.gensalt(1))
+            password_hash = bcrypt.hashpw(password, bcrypt.gensalt())
 
         if localpart:
             yield self.check_username(localpart)