diff --git a/config/autoload/templates.global.php b/config/autoload/templates.global.php
index cf8e404b..24296d41 100644
--- a/config/autoload/templates.global.php
+++ b/config/autoload/templates.global.php
@@ -4,6 +4,9 @@ return [
 
     'templates' => [
         'extension' => 'phtml',
+    ],
+
+    'plates' => [
         'extensions' => [
             // extension service names or instances
         ],
diff --git a/module/Common/config/templates.config.php b/module/Common/config/templates.config.php
index 37a6714d..eb25ef78 100644
--- a/module/Common/config/templates.config.php
+++ b/module/Common/config/templates.config.php
@@ -5,7 +5,7 @@ use Shlinkio\Shlink\Common\Template\Extension\TranslatorExtension;
 
 return [
 
-    'templates' => [
+    'plates' => [
         'extensions' => [
             TranslatorExtension::class,
         ],
diff --git a/module/Core/templates/error/404.html.twig b/module/Core/templates/error/404.html.twig
deleted file mode 100644
index fe36f047..00000000
--- a/module/Core/templates/error/404.html.twig
+++ /dev/null
@@ -1,17 +0,0 @@
-{% extends 'core/layout/default.html.twig' %}
-
-{% block title %}{{ translate('URL Not Found') }}{% endblock %}
-
-{% block stylesheets %}
-    <style>
-        p {margin-bottom: 20px;}
-        body {text-align: center;}
-    </style>
-{% endblock %}
-
-{% block content %}
-    <h1>{{ translate('Oops!') }}</h1>
-    <hr>
-    <p>{{ translate('This short URL doesn\'t seem to be valid.') }}</p>
-    <p>{{ translate('Make sure you included all the characters, with no extra punctuation.') }}</p>
-{% endblock %}
diff --git a/module/Core/templates/error/404.phtml b/module/Core/templates/error/404.phtml
new file mode 100644
index 00000000..369a168b
--- /dev/null
+++ b/module/Core/templates/error/404.phtml
@@ -0,0 +1,19 @@
+<?php $this->layout('ShlinkCore::layout/default') ?>
+
+<?php $this->start('title') ?>
+    <?= $this->translate('URL Not Found') ?>
+<?php $this->end() ?>
+
+<?php $this->start('stylesheets') ?>
+    <style>
+        p {margin-bottom: 20px;}
+        body {text-align: center;}
+    </style>
+<?php $this->end() ?>
+
+<?php $this->start('main') ?>
+    <h1><?= $this->translate('Oops!') ?></h1>
+    <hr>
+    <p><?= $this->translate('This short URL doesn\'t seem to be valid.') ?></p>
+    <p><?= $this->translate('Make sure you included all the characters, with no extra punctuation.') ?></p>
+<?php $this->end() ?>
diff --git a/module/Core/templates/error/error.html.twig b/module/Core/templates/error/error.html.twig
deleted file mode 100644
index 5cb66c57..00000000
--- a/module/Core/templates/error/error.html.twig
+++ /dev/null
@@ -1,21 +0,0 @@
-{% extends 'core/layout/default.html.twig' %}
-
-{% block title %}{{ status }} {{ reason }}{% endblock %}
-
-{% block stylesheets %}
-    <style>
-        p {margin-bottom: 20px;}
-        body {text-align: center;}
-    </style>
-{% endblock %}
-
-{% block content %}
-    <h1>{{ translate('Oops!') }}</h1>
-    <hr>
-    {% if status != 404 %}
-        <p>{{ translate('We encountered a %s %s error.') | format(status, reason) }}</p>
-    {% else %}
-        <p>{{ translate('This short URL doesn\'t seem to be valid.') }}</p>
-        <p>{{ translate('Make sure you included all the characters, with no extra punctuation.') }}</p>
-    {% endif %}
-{% endblock %}
diff --git a/module/Core/templates/error/error.phtml b/module/Core/templates/error/error.phtml
new file mode 100644
index 00000000..6d22ed9f
--- /dev/null
+++ b/module/Core/templates/error/error.phtml
@@ -0,0 +1,25 @@
+<?php $this->layout('ShlinkCore::layout/default') ?>
+
+<?php $this->start('title') ?>
+    <?= $this->e($status . ' ' . $reason) ?>
+<?php $this->end() ?>
+
+<?php $this->start('stylesheets') ?>
+    <style>
+        p {margin-bottom: 20px;}
+        body {text-align: center;}
+    </style>
+<?php $this->end() ?>
+
+<?php $this->start('main') ?>
+    <h1><?= $this->translate('Oops!') ?></h1>
+    <hr>
+
+    <?php if ($status !== 404): ?>
+        <p><?= sprintf($this->translate('We encountered a %s %s error.'), $status, $reason) ?></p>
+    <?php else: ?>
+        <p><?= $this->translate('This short URL doesn\'t seem to be valid.') ?></p>
+        <p><?= $this->translate('Make sure you included all the characters, with no extra punctuation.') ?></p>
+    <?php endif; ?>
+<?php $this->end() ?>
+
diff --git a/module/Core/templates/layout/default.html.twig b/module/Core/templates/layout/default.phtml
similarity index 70%
rename from module/Core/templates/layout/default.html.twig
rename to module/Core/templates/layout/default.phtml
index 4b405c5b..802bf466 100644
--- a/module/Core/templates/layout/default.html.twig
+++ b/module/Core/templates/layout/default.phtml
@@ -3,7 +3,7 @@
 <head>
     <meta charset="utf-8" />
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
-    <title>{% block title %}{% endblock %} | URL shortener</title>
+    <title><?= $this->section('title', '') ?> | URL shortener</title>
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />
     <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css" />
@@ -13,28 +13,30 @@
         .app-content {flex: 1;}
         .app-footer p {margin-bottom: 20px;}
     </style>
-    {% block stylesheets %}{% endblock %}
+    <?= $this->section('stylesheets', '') ?>
 </head>
 <body class="app">
     <div class="app-content">
         <main class="container">
-            {% block content %}{% endblock %}
+            <?= $this->section('main', '') ?>
         </main>
     </div>
 
     <footer class="app-footer">
         <div class="container">
             <hr />
-            {% block footer %}
+            <?php if ($this->section('footer')): ?>
+                <?= $this->section('footer') ?>
+            <?php else: ?>
                 <p>
-                    &copy; {{ "now" | date("Y") }} <a href="https://shlink.io">Shlink</a>
+                    &copy; <?= date('Y') ?> <a href="https://shlink.io">Shlink</a>
                 </p>
-            {% endblock %}
+            <?php endif; ?>
         </div>
     </footer>
 
     <script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
     <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
-    {% block javascript %}{% endblock %}
+    <?= $this->section('javascript', '') ?>
 </body>
 </html>
diff --git a/module/Rest/src/Middleware/PathVersionMiddleware.php b/module/Rest/src/Middleware/PathVersionMiddleware.php
index 3220bfaf..b247f50c 100644
--- a/module/Rest/src/Middleware/PathVersionMiddleware.php
+++ b/module/Rest/src/Middleware/PathVersionMiddleware.php
@@ -37,7 +37,7 @@ class PathVersionMiddleware implements MiddlewareInterface
         $uri = $request->getUri();
         $path = $uri->getPath();
 
-        // If the path does not begin with the version number, prepend v1 by default for retrocompatibility purposes
+        // If the path does not begin with the version number, prepend v1 by default for BC compatibility purposes
         if (strpos($path, '/v') !== 0) {
             $parts = explode('/', $path);
             // Remove the first empty part and the
diff --git a/public/index.php b/public/index.php
index 6b310943..3f2c0f84 100644
--- a/public/index.php
+++ b/public/index.php
@@ -1,9 +1,9 @@
 <?php
+declare(strict_types=1);
+
 use Interop\Container\ContainerInterface;
 use Zend\Expressive\Application;
 
 /** @var ContainerInterface $container */
 $container = include __DIR__ . '/../config/container.php';
-/** @var Application $app */
-$app = $container->get(Application::class);
-$app->run();
+$app = $container->get(Application::class)->run();