diff --git a/Transformer/ModelToElasticaAutoTransformer.php b/Transformer/ModelToElasticaAutoTransformer.php
index 6a8a381..910d1cf 100644
--- a/Transformer/ModelToElasticaAutoTransformer.php
+++ b/Transformer/ModelToElasticaAutoTransformer.php
@@ -49,8 +49,8 @@ class ModelToElasticaAutoTransformer implements ModelToElasticaTransformerInterf
             if (!method_exists($class, $getter)) {
                 throw new RuntimeException(sprintf('The getter %s::%s does not exist', $class, $getter));
             }
-            if ($value = $this->normalizeValue($object->$getter()) !== null) {
-                $array[$key] = $this->normalizeValue($object->$getter());
+            if (null !== $value = $this->normalizeValue($object->$getter())) {
+                $array[$key] = $value;
             }
         }
         $identifierGetter = 'get'.ucfirst($this->options['identifier']);
@@ -71,7 +71,7 @@ class ModelToElasticaAutoTransformer implements ModelToElasticaTransformerInterf
         $normalizeValue = function(&$v) {
             if ($v instanceof \DateTime) {
                 $v = (int) $v->format('U');
-            } elseif (!is_int($v) && !is_float($v) && !is_bool($v) && !is_null($v)) {
+            } elseif (!is_scalar($v) && !is_null($v)) {
                 $v = (string) $v;
             }
         };