Fix #1767

middleman-core/lib/middleman-core/preview_server.rb

@@ -163,6 +163,7 @@ module Middleman
                                   path: root,
                                   only: match_against
 
+            unless config[:watcher_disable]
               # Hack around node_modules in root.
               watcher.listener.ignore(/^node_modules/)
 
@@ -173,6 +174,7 @@ module Middleman
               watcher.listener.ignore(/^vendor\/bundle/)
             end
           end
+        end
 
         # store configured port to make a check later on possible
         configured_port = app.config[:port]