diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeZoneToStringTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeZoneToStringTransformer.php
index 32fa5d1129..bec7509fb7 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeZoneToStringTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeZoneToStringTransformer.php
@@ -17,7 +17,7 @@ use Symfony\Component\Form\Exception\TransformationFailedException;
 /**
  * Transforms between a timezone identifier string and a DateTimeZone object.
  *
- * @author Roland Franssen <franssen.roland@gmai.com>
+ * @author Roland Franssen <franssen.roland@gmail.com>
  */
 class DateTimeZoneToStringTransformer implements DataTransformerInterface
 {
@@ -39,14 +39,14 @@ class DateTimeZoneToStringTransformer implements DataTransformerInterface
 
         if ($this->multiple) {
             if (!\is_array($dateTimeZone)) {
-                throw new TransformationFailedException('Expected an array.');
+                throw new TransformationFailedException('Expected an array of \DateTimeZone objects.');
             }
 
             return array_map([new self(), 'transform'], $dateTimeZone);
         }
 
         if (!$dateTimeZone instanceof \DateTimeZone) {
-            throw new TransformationFailedException('Expected a \DateTimeZone.');
+            throw new TransformationFailedException('Expected a \DateTimeZone object.');
         }
 
         return $dateTimeZone->getName();
@@ -63,14 +63,14 @@ class DateTimeZoneToStringTransformer implements DataTransformerInterface
 
         if ($this->multiple) {
             if (!\is_array($value)) {
-                throw new TransformationFailedException('Expected an array.');
+                throw new TransformationFailedException('Expected an array of timezone identifier strings.');
             }
 
             return array_map([new self(), 'reverseTransform'], $value);
         }
 
         if (!\is_string($value)) {
-            throw new TransformationFailedException('Expected a string.');
+            throw new TransformationFailedException('Expected a timezone identifier string.');
         }
 
         try {