diff --git a/app/models/dmsf_folder.rb b/app/models/dmsf_folder.rb
index 71a20a9b..3a48cf58 100644
--- a/app/models/dmsf_folder.rb
+++ b/app/models/dmsf_folder.rb
@@ -206,7 +206,9 @@ class DmsfFolder < ActiveRecord::Base
     tree = [[l(:link_documents), nil]]
     project_id = (project.is_a?(Project)) ? project.id : project
     folders = DmsfFolder.where(project_id: project_id, dmsf_folder_id: nil).visible(false).to_a
+    # TODO: This prevents copying folders into its sub-folders too. It should be allowed.
     folders.delete(current_folder)
+    #
     folders = folders.delete_if{ |f| f.locked_for_user? }
     folders.each do |folder|
       tree.push(["...#{folder.title}", folder.id])
diff --git a/lib/redmine_dmsf/lockable.rb b/lib/redmine_dmsf/lockable.rb
index fae03947..e15a1401 100644
--- a/lib/redmine_dmsf/lockable.rb
+++ b/lib/redmine_dmsf/lockable.rb
@@ -37,8 +37,8 @@ module RedmineDmsf
           ret << lock unless lock.expired?
         end
       end
-      if tree
-        ret = ret | (self.dmsf_folder.locks.empty? ? self.dmsf_folder.lock : self.dmsf_folder.locks) if dmsf_folder
+      if tree && dmsf_folder
+        ret = ret | (dmsf_folder.locks.empty? ? dmsf_folder.lock : dmsf_folder.locks)
       end
       ret
     end