diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index ea3f460c4692..7185d75e9220 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -1037,8 +1037,8 @@ public function getPort()
             $pos = strrpos($host, ':');
         }
 
-        if (false !== $pos) {
-            return (int) substr($host, $pos + 1);
+        if (false !== $pos && $port = substr($host, $pos + 1)) {
+            return (int) $port;
         }
 
         return 'https' === $this->getScheme() ? 443 : 80;
diff --git a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
index d266e1f68a4c..650d8fca7dba 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
@@ -2427,6 +2427,18 @@ public function testTrustedPort()
 
         $this->assertSame(443, $request->getPort());
     }
+
+    public function testTrustedPortDoesNotDefaultToZero()
+    {
+        Request::setTrustedProxies(['1.1.1.1'], Request::HEADER_X_FORWARDED_ALL);
+
+        $request = Request::create('/');
+        $request->server->set('REMOTE_ADDR', '1.1.1.1');
+        $request->headers->set('X-Forwarded-Host', 'test.example.com');
+        $request->headers->set('X-Forwarded-Port', null);
+
+        $this->assertSame(80, $request->getPort());
+    }
 }
 
 class RequestContentProxy extends Request