diff --git a/demo/start.sh b/demo/start.sh
index b5dea5e176..572dbfab0b 100755
--- a/demo/start.sh
+++ b/demo/start.sh
@@ -23,7 +23,6 @@ for port in 8080 8081 8082; do
     #rm $DIR/etc/$port.config
     python -m synapse.app.homeserver \
         --generate-config \
-        --enable_registration \
         -H "localhost:$https_port" \
         --config-path "$DIR/etc/$port.config" \
 
@@ -36,6 +35,8 @@ for port in 8080 8081 8082; do
         fi
     fi
 
+    perl -p -i -e 's/^enable_registration:.*/enable_registration: true/g' $DIR/etc/$port.config
+
     python -m synapse.app.homeserver \
         --config-path "$DIR/etc/$port.config" \
         -D \