diff --git a/test/date_format-test.js b/test/date_format-test.js
index d4a5cb5..444446d 100644
--- a/test/date_format-test.js
+++ b/test/date_format-test.js
@@ -39,6 +39,12 @@ vows.describe('date_format').addBatch({
         dateFormat.asString(dateFormat.ABSOLUTETIME_FORMAT, date),
         '14:31:30.005'
       );
+    },
+    'should provide a custom format': function(date) {
+      assert.equal(
+        dateFormat.asString("O.SSS.ss.mm.hh.dd.MM.yy", date),
+        '+1100.005.30.31.14.11.01.10'
+      );
     }
   }
 }).export(module);