diff --git a/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php b/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
index 25dcd228694c..c0dd358e8511 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
@@ -86,7 +86,7 @@ public function remove($name)
         $retval = null;
         $attributes = & $this->resolveAttributePath($name);
         $name = $this->resolveKey($name);
-        if (array_key_exists($name, $attributes)) {
+        if (null !== $attributes && array_key_exists($name, $attributes)) {
             $retval = $attributes[$name];
             unset($attributes[$name]);
         }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Session/Attribute/NamespacedAttributeBagTest.php b/src/Symfony/Component/HttpFoundation/Tests/Session/Attribute/NamespacedAttributeBagTest.php
index c11d0d65136f..0c46a515a0c2 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Session/Attribute/NamespacedAttributeBagTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/Session/Attribute/NamespacedAttributeBagTest.php
@@ -143,6 +143,16 @@ public function testRemove()
         $this->assertNull($this->bag->get('user.login'));
     }
 
+    public function testRemoveExistingNamespacedAttribute()
+    {
+        $this->assertSame('cod', $this->bag->remove('category/fishing/first'));
+    }
+
+    public function testRemoveNonexistingNamespacedAttribute()
+    {
+        $this->assertNull($this->bag->remove('foo/bar/baz'));
+    }
+
     public function testClear()
     {
         $this->bag->clear();