diff --git a/lib/redmine/views/builders/xml.rb b/lib/redmine/views/builders/xml.rb
index 5814d00cb..2bd32c1bf 100644
--- a/lib/redmine/views/builders/xml.rb
+++ b/lib/redmine/views/builders/xml.rb
@@ -29,7 +29,7 @@ module Redmine
         end
 
         def method_missing(sym, *args, &block)
-          if args.size == 1 && args.first.is_a?(Time)
+          if args.size == 1 && args.first.is_a?(::Time)
             __send__ sym, args.first.xmlschema, &block
           else
             super