diff --git a/lib/redmine/views/builders/structure.rb b/lib/redmine/views/builders/structure.rb
index 99db94be2..3a2ae544a 100644
--- a/lib/redmine/views/builders/structure.rb
+++ b/lib/redmine/views/builders/structure.rb
@@ -69,8 +69,7 @@ module Redmine
               end
             end
           end
-
-          if block
+          if block_given?
             @struct << (args.first.is_a?(Hash) ? args.first : {})
             yield(self)
             ret = @struct.pop