diff --git a/test/unit/watcher_test.rb b/test/unit/watcher_test.rb
index db73f8ccc..d0fe588bf 100644
--- a/test/unit/watcher_test.rb
+++ b/test/unit/watcher_test.rb
@@ -47,6 +47,12 @@ class WatcherTest < ActiveSupport::TestCase
     assert Issue.watched_by(@user).include?(@issue)
   end
   
+  def test_watcher_user_ids
+    issue = Issue.new
+    issue.watcher_user_ids = ['1', '3']
+    assert issue.watched_by?(User.find(1))
+  end
+  
   def test_recipients
     @issue.watchers.delete_all
     @issue.reload
diff --git a/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb b/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb
index f99f4a60d..b4ac776ec 100644
--- a/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb
+++ b/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb
@@ -50,9 +50,9 @@ module Redmine
           watching ? add_watcher(user) : remove_watcher(user)
         end
         
-        # Returns true if object is watched by user
+        # Returns true if object is watched by +user+
         def watched_by?(user)
-          !!(user && self.watchers.detect {|w| w.user_id == user.id })
+          !!(user && self.watcher_user_ids.detect {|uid| uid == user.id })
         end
         
         # Returns an array of watchers' email addresses