diff --git a/module/Common/src/Middleware/LocaleMiddleware.php b/module/Common/src/Middleware/LocaleMiddleware.php
index 20f796ff..0cb81502 100644
--- a/module/Common/src/Middleware/LocaleMiddleware.php
+++ b/module/Common/src/Middleware/LocaleMiddleware.php
@@ -2,10 +2,11 @@
 namespace Shlinkio\Shlink\Common\Middleware;
 
 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 Zend\I18n\Translator\Translator;
-use Zend\Stratigility\MiddlewareInterface;
 
 class LocaleMiddleware implements MiddlewareInterface
 {
@@ -25,40 +26,26 @@ class LocaleMiddleware implements MiddlewareInterface
         $this->translator = $translator;
     }
 
+
+
     /**
-     * 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)
     {
         if (! $request->hasHeader('Accept-Language')) {
-            return $out($request, $response);
+            return $delegate->process($request);
         }
 
         $locale = $request->getHeaderLine('Accept-Language');
         $this->translator->setLocale($this->normalizeLocale($locale));
-        return $out($request, $response);
+        return $delegate->process($request);
     }
 
     /**
diff --git a/module/Common/test/Middleware/LocaleMiddlewareTest.php b/module/Common/test/Middleware/LocaleMiddlewareTest.php
index 4d9e81ce..762dc31f 100644
--- a/module/Common/test/Middleware/LocaleMiddlewareTest.php
+++ b/module/Common/test/Middleware/LocaleMiddlewareTest.php
@@ -3,7 +3,7 @@ namespace ShlinkioTest\Shlink\Common\Middleware;
 
 use PHPUnit\Framework\TestCase;
 use Shlinkio\Shlink\Common\Middleware\LocaleMiddleware;
-use Zend\Diactoros\Response;
+use ShlinkioTest\Shlink\Common\Util\TestUtils;
 use Zend\Diactoros\ServerRequestFactory;
 use Zend\I18n\Translator\Translator;
 
@@ -30,9 +30,7 @@ class LocaleMiddlewareTest extends TestCase
     public function whenNoHeaderIsPresentLocaleIsNotChanged()
     {
         $this->assertEquals('ru', $this->translator->getLocale());
-        $this->middleware->__invoke(ServerRequestFactory::fromGlobals(), new Response(), function ($req, $resp) {
-            return $resp;
-        });
+        $this->middleware->process(ServerRequestFactory::fromGlobals(), TestUtils::createDelegateMock()->reveal());
         $this->assertEquals('ru', $this->translator->getLocale());
     }
 
@@ -43,9 +41,7 @@ class LocaleMiddlewareTest extends TestCase
     {
         $this->assertEquals('ru', $this->translator->getLocale());
         $request = ServerRequestFactory::fromGlobals()->withHeader('Accept-Language', 'es');
-        $this->middleware->__invoke($request, new Response(), function ($req, $resp) {
-            return $resp;
-        });
+        $this->middleware->process($request, TestUtils::createDelegateMock()->reveal());
         $this->assertEquals('es', $this->translator->getLocale());
     }
 
@@ -54,18 +50,16 @@ class LocaleMiddlewareTest extends TestCase
      */
     public function localeGetsNormalized()
     {
+        $delegate = TestUtils::createDelegateMock();
+
         $this->assertEquals('ru', $this->translator->getLocale());
 
         $request = ServerRequestFactory::fromGlobals()->withHeader('Accept-Language', 'es_ES');
-        $this->middleware->__invoke($request, new Response(), function ($req, $resp) {
-            return $resp;
-        });
+        $this->middleware->process($request, $delegate->reveal());
         $this->assertEquals('es', $this->translator->getLocale());
 
         $request = ServerRequestFactory::fromGlobals()->withHeader('Accept-Language', 'en-US');
-        $this->middleware->__invoke($request, new Response(), function ($req, $resp) {
-            return $resp;
-        });
+        $this->middleware->process($request, $delegate->reveal());
         $this->assertEquals('en', $this->translator->getLocale());
     }
 }
diff --git a/module/Common/test/Util/TestUtils.php b/module/Common/test/Util/TestUtils.php
new file mode 100644
index 00000000..8bd4969d
--- /dev/null
+++ b/module/Common/test/Util/TestUtils.php
@@ -0,0 +1,35 @@
+<?php
+namespace ShlinkioTest\Shlink\Common\Util;
+
+use Interop\Http\ServerMiddleware\DelegateInterface;
+use Prophecy\Argument;
+use Prophecy\Prophet;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use Zend\Diactoros\Response;
+
+class TestUtils
+{
+    private static $prophet;
+
+    public static function createDelegateMock(ResponseInterface $response = null, RequestInterface $request = null)
+    {
+        $argument = $request ?: Argument::any();
+        $delegate = static::getProphet()->prophesize(DelegateInterface::class);
+        $delegate->process($argument)->willReturn($response ?: new Response());
+
+        return $delegate;
+    }
+
+    /**
+     * @return Prophet
+     */
+    private static function getProphet()
+    {
+        if (static::$prophet === null) {
+            static::$prophet = new Prophet();
+        }
+
+        return static::$prophet;
+    }
+}