diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index 2bf52ce4339df..10f779d279ec0 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -522,10 +522,10 @@ public function __toString()
         $cookies = [];
 
         foreach ($this->cookies as $k => $v) {
-            $cookies[] = $k.'='.$v;
+            $cookies[] = \is_array($v) ? http_build_query([$k => $v], '', '; ', \PHP_QUERY_RFC3986) : "$k=$v";
         }
 
-        if (!empty($cookies)) {
+        if ($cookies) {
             $cookieHeader = 'Cookie: '.implode('; ', $cookies)."\r\n";
         }
 
diff --git a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
index df55628c6d15d..058b5419a87f9 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
@@ -1702,6 +1702,12 @@ public function testToString()
         $asString = (string) $request;
 
         $this->assertStringContainsString('Cookie: Foo=Bar; Another=Cookie', $asString);
+
+        $request->cookies->set('foo.bar', [1, 2]);
+
+        $asString = (string) $request;
+
+        $this->assertStringContainsString('foo.bar%5B0%5D=1; foo.bar%5B1%5D=2', $asString);
     }
 
     public function testIsMethod()