diff --git a/module/Core/src/Action/PreviewAction.php b/module/Core/src/Action/PreviewAction.php
index f2145e1b..291225be 100644
--- a/module/Core/src/Action/PreviewAction.php
+++ b/module/Core/src/Action/PreviewAction.php
@@ -2,16 +2,16 @@
 namespace Shlinkio\Shlink\Core\Action;
 
 use Acelaya\ZsmAnnotatedServices\Annotation\Inject;
+use Interop\Http\ServerMiddleware\DelegateInterface;
+use Interop\Http\ServerMiddleware\MiddlewareInterface;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
-use Shlinkio\Shlink\Common\Exception\PreviewGenerationException;
 use Shlinkio\Shlink\Common\Service\PreviewGenerator;
 use Shlinkio\Shlink\Common\Service\PreviewGeneratorInterface;
 use Shlinkio\Shlink\Common\Util\ResponseUtilsTrait;
 use Shlinkio\Shlink\Core\Exception\InvalidShortCodeException;
 use Shlinkio\Shlink\Core\Service\UrlShortener;
 use Shlinkio\Shlink\Core\Service\UrlShortenerInterface;
-use Zend\Stratigility\MiddlewareInterface;
 
 class PreviewAction implements MiddlewareInterface
 {
@@ -40,44 +40,28 @@ class PreviewAction implements MiddlewareInterface
     }
 
     /**
-     * Process an incoming request and/or response.
-     *
-     * Accepts a server-side request and a response instance, and does
-     * something with them.
-     *
-     * If the response is not complete and/or further processing would not
-     * interfere with the work done in the middleware, or if the middleware
-     * wants to delegate to another process, it can use the `$out` callable
-     * if present.
-     *
-     * If the middleware does not return a value, execution of the current
-     * request is considered complete, and the response instance provided will
-     * be considered the response to return.
-     *
-     * Alternately, the middleware may return a response instance.
-     *
-     * Often, middleware will `return $out();`, with the assumption that a
-     * later middleware will return a response.
+     * Process an incoming server request and return a response, optionally delegating
+     * to the next middleware component to create the response.
      *
      * @param Request $request
-     * @param Response $response
-     * @param null|callable $out
-     * @return null|Response
+     * @param DelegateInterface $delegate
+     *
+     * @return Response
      */
-    public function __invoke(Request $request, Response $response, callable $out = null)
+    public function process(Request $request, DelegateInterface $delegate)
     {
         $shortCode = $request->getAttribute('shortCode');
 
         try {
             $url = $this->urlShortener->shortCodeToUrl($shortCode);
             if (! isset($url)) {
-                return $out($request, $response->withStatus(404), 'Not found');
+                return $delegate->process($request);
             }
 
             $imagePath = $this->previewGenerator->generatePreview($url);
             return $this->generateImageResponse($imagePath);
         } catch (InvalidShortCodeException $e) {
-            return $out($request, $response->withStatus(404), 'Not found');
+            return $delegate->process($request);
         }
     }
 }
diff --git a/module/Core/test/Action/PreviewActionTest.php b/module/Core/test/Action/PreviewActionTest.php
index 8ef2883a..a5e57d2d 100644
--- a/module/Core/test/Action/PreviewActionTest.php
+++ b/module/Core/test/Action/PreviewActionTest.php
@@ -2,12 +2,14 @@
 namespace ShlinkioTest\Shlink\Core\Action;
 
 use PHPUnit\Framework\TestCase;
+use Prophecy\Argument;
 use Prophecy\Prophecy\ObjectProphecy;
 use Shlinkio\Shlink\Common\Exception\PreviewGenerationException;
 use Shlinkio\Shlink\Common\Service\PreviewGenerator;
 use Shlinkio\Shlink\Core\Action\PreviewAction;
 use Shlinkio\Shlink\Core\Exception\InvalidShortCodeException;
 use Shlinkio\Shlink\Core\Service\UrlShortener;
+use ShlinkioTest\Shlink\Common\Util\TestUtils;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequestFactory;
 
@@ -36,20 +38,18 @@ class PreviewActionTest extends TestCase
     /**
      * @test
      */
-    public function invalidShortCodeFallbacksToNextMiddlewareWithStatusNotFound()
+    public function invalidShortCodeFallsBackToNextMiddleware()
     {
         $shortCode = 'abc123';
         $this->urlShortener->shortCodeToUrl($shortCode)->willReturn(null)->shouldBeCalledTimes(1);
+        $delegate = TestUtils::createDelegateMock();
 
-        $resp = $this->action->__invoke(
+        $this->action->process(
             ServerRequestFactory::fromGlobals()->withAttribute('shortCode', $shortCode),
-            new Response(),
-            function ($req, $resp) {
-                return $resp;
-            }
+            $delegate->reveal()
         );
 
-        $this->assertEquals(404, $resp->getStatusCode());
+        $delegate->process(Argument::cetera())->shouldHaveBeenCalledTimes(1);
     }
 
     /**
@@ -63,9 +63,9 @@ class PreviewActionTest extends TestCase
         $this->urlShortener->shortCodeToUrl($shortCode)->willReturn($url)->shouldBeCalledTimes(1);
         $this->previewGenerator->generatePreview($url)->willReturn($path)->shouldBeCalledTimes(1);
 
-        $resp = $this->action->__invoke(
+        $resp = $this->action->process(
             ServerRequestFactory::fromGlobals()->withAttribute('shortCode', $shortCode),
-            new Response()
+            TestUtils::createDelegateMock()->reveal()
         );
 
         $this->assertEquals(filesize($path), $resp->getHeaderLine('Content-length'));
@@ -75,20 +75,18 @@ class PreviewActionTest extends TestCase
     /**
      * @test
      */
-    public function invalidShortcodeExceptionReturnsNotFound()
+    public function invalidShortcodeExceptionFallsBackToNextMiddleware()
     {
         $shortCode = 'abc123';
         $this->urlShortener->shortCodeToUrl($shortCode)->willThrow(InvalidShortCodeException::class)
                                                        ->shouldBeCalledTimes(1);
+        $delegate = TestUtils::createDelegateMock();
 
-        $resp = $this->action->__invoke(
+        $this->action->process(
             ServerRequestFactory::fromGlobals()->withAttribute('shortCode', $shortCode),
-            new Response(),
-            function ($req, $resp) {
-                return $resp;
-            }
+            $delegate->reveal()
         );
 
-        $this->assertEquals(404, $resp->getStatusCode());
+        $delegate->process(Argument::any())->shouldHaveBeenCalledTimes(1);
     }
 }