diff --git a/README.md b/README.md
index 131b1b4..59324d6 100644
--- a/README.md
+++ b/README.md
@@ -636,3 +636,61 @@ class Client extends BaseClient
     }
 }
 ```
+
+### Example of Advanced Query
+
+If you would like to perform more advanced queries, here is one example using
+the snowball stemming algorithm.
+
+It searches for Article entities using `title`, `tags`, and `categoryIds`.
+Results must match at least one specified `categoryIds`, and should match the
+`title` or `tags` criteria. Additionally, we define a snowball analyzer to
+apply to queries against the `title` field.
+
+```php
+$finder = $this->container->get('foq_elastica.finder.website.article');
+$boolQuery = new \Elastica_Query_Bool();
+
+$fieldQuery = new \Elastica_Query_Text();
+$fieldQuery->setFieldQuery('title', 'I am a title string');
+$fieldQuery->setFieldParam('title', 'analyzer', 'my_analyzer');
+$boolQuery->addShould($fieldQuery);
+
+$tagsQuery = new \Elastica_Query_Terms();
+$tagsQuery->setTerms('tags', array('tag1', 'tag2'));
+$boolQuery->addShould($tagsQuery);
+
+$categoryQuery = new \Elastica_Query_Terms();
+$categoryQuery->setTerms('categoryIds', array('1', '2', '3'));
+$boolQuery->addMust($categoryQuery);
+
+$data = $finder->find($boolQuery);
+```
+
+Configuration:
+
+```yaml
+foq_elastica:
+    clients:
+        default: { host: localhost, port: 9200 }
+    indexes:
+        site:
+            settings:
+                index:
+                  analysis:
+                        analyzer:
+                            my_analyzer:
+                                type: snowball
+                                language: English
+            types:
+                article:
+                    mappings:
+                        title: { boost: 10, analyzer: my_analyzer }
+                        tags:
+                        categoryIds:
+                    persistence:
+                        driver: orm
+                        model: Acme\DemoBundle\Entity\Article
+                        provider:
+                        finder:
+```
diff --git a/Transformer/ModelToElasticaAutoTransformer.php b/Transformer/ModelToElasticaAutoTransformer.php
index e65d59d..1666beb 100644
--- a/Transformer/ModelToElasticaAutoTransformer.php
+++ b/Transformer/ModelToElasticaAutoTransformer.php
@@ -107,7 +107,7 @@ class ModelToElasticaAutoTransformer implements ModelToElasticaTransformerInterf
         $normalizeValue = function(&$v)
         {
             if ($v instanceof \DateTime) {
-                $v = (int)$v->format('U');
+                $v = $v->format('v');
             } elseif (!is_scalar($v) && !is_null($v)) {
                 $v = (string)$v;
             }