diff --git a/lib/jekyll/core_ext.rb b/lib/jekyll/core_ext.rb
index 18159fbf..ead448a4 100644
--- a/lib/jekyll/core_ext.rb
+++ b/lib/jekyll/core_ext.rb
@@ -19,4 +19,12 @@ class Hash
 
     target
   end
-end
\ No newline at end of file
+end
+
+# Thanks, ActiveSupport!
+class Date
+  # Converts datetime to an appropriate format for use in XML
+  def xmlschema
+    strftime("%Y-%m-%dT%H:%M:%S%Z")
+  end if RUBY_VERSION < '1.9'
+end