diff --git a/src/Symfony/Component/DependencyInjection/Definition.php b/src/Symfony/Component/DependencyInjection/Definition.php
index e68e8b3cb8..4e99cca77a 100644
--- a/src/Symfony/Component/DependencyInjection/Definition.php
+++ b/src/Symfony/Component/DependencyInjection/Definition.php
@@ -649,6 +649,10 @@ class Definition
             @trigger_error('The '.__METHOD__.' method is deprecated since version 2.8 and will be removed in 3.0.', E_USER_DEPRECATED);
         }
 
+        if (ContainerInterface::SCOPE_PROTOTYPE === $scope) {
+            $this->setShared(false);
+        }
+
         $this->scope = $scope;
 
         return $this;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/DefinitionTest.php b/src/Symfony/Component/DependencyInjection/Tests/DefinitionTest.php
index 4bac0e2a0b..d67f1d7224 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/DefinitionTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/DefinitionTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\DependencyInjection\Tests;
 
 use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 class DefinitionTest extends \PHPUnit_Framework_TestCase
 {
@@ -139,6 +140,18 @@ class DefinitionTest extends \PHPUnit_Framework_TestCase
         $this->assertFalse($def->isShared(), '->isShared() returns false if the instance must not be shared');
     }
 
+    /**
+     * @group legacy
+     */
+    public function testPrototypeScopedDefinitionAreNotShared()
+    {
+        $def = new Definition('stdClass');
+        $def->setScope(ContainerInterface::SCOPE_PROTOTYPE);
+
+        $this->assertFalse($def->isShared());
+        $this->assertEquals(ContainerInterface::SCOPE_PROTOTYPE, $def->getScope());
+    }
+
     /**
      * @covers Symfony\Component\DependencyInjection\Definition::setScope
      * @covers Symfony\Component\DependencyInjection\Definition::getScope
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/legacy-services9.xml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/legacy-services9.xml
index dc55972a28..dcb312a1e9 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/legacy-services9.xml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/legacy-services9.xml
@@ -33,6 +33,6 @@
       <configurator class="%baz_class%" method="configureStatic1"/>
     </service>
     <service id="factory_service" class="Bar" factory-method="getInstance" factory-service="foo.baz"/>
-    <service id="foo_bar" class="%foo_class%" scope="prototype"/>
+    <service id="foo_bar" class="%foo_class%" shared="false" scope="prototype"/>
   </services>
 </container>
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/legacy-services9.yml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/legacy-services9.yml
index 6a5f03d9b8..c7e80ea5b8 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/legacy-services9.yml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/legacy-services9.yml
@@ -29,4 +29,5 @@ services:
         factory_service: foo.baz
     foo_bar:
         class: %foo_class%
+        shared: false
         scope: prototype