diff --git a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
index 4236b72f25..4677a61ca4 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
@@ -496,7 +496,7 @@ class XmlFileLoader extends FileLoader
 
             switch ($arg->getAttribute('type')) {
                 case 'service':
-                    if (!$arg->getAttribute('id')) {
+                    if ('' === $arg->getAttribute('id')) {
                         throw new InvalidArgumentException(sprintf('Tag "<%s>" with type="service" has no or empty "id" attribute in "%s".', $name, $file));
                     }
                     if ($arg->hasAttribute('strict')) {
@@ -549,7 +549,7 @@ class XmlFileLoader extends FileLoader
      * @param \DOMNode $node
      * @param mixed    $name
      *
-     * @return array
+     * @return \DOMElement[]
      */
     private function getChildren(\DOMNode $node, $name)
     {
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
index cffd5df605..c85b7a7c01 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
@@ -61,5 +61,9 @@
     </service>
     <service id="alias_for_foo" alias="foo" />
     <service id="another_alias_for_foo" alias="foo" public="false" />
+    <service id="0" class="FooClass" />
+    <service id="1" class="FooClass">
+      <argument type="service" id="0" />
+    </service>
   </services>
 </container>