diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 770b5d94..748b8c4f 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -6,7 +6,7 @@
 use Symfony\Component\Config\Definition\ConfigurationInterface;
 
 /**
- * TinymceBundle configuration structure.
+ * Configuration.
  */
 class Configuration implements ConfigurationInterface
 {
@@ -15,14 +15,14 @@ class Configuration implements ConfigurationInterface
      *
      * @return TreeBuilder
      */
-    public function getConfigTreeBuilder()
+    public function getConfigTreeBuilder(): TreeBuilder
     {
         $defaults = $this->getTinymceDefaults();
 
-        $treeBuilder = new TreeBuilder('stfalcon_tinymce');
+        $treeBuilder = new TreeBuilder();
 
         return $treeBuilder
-            ->getRootNode()
+            ->root('stfalcon_tinymce', 'array')
                 ->children()
                     // Include jQuery (true) library or not (false)
                     ->booleanNode('include_jquery')->defaultFalse()->end()
@@ -79,23 +79,23 @@ public function getConfigTreeBuilder()
      *
      * @return array
      */
-    private function getTinymceDefaults()
+    private function getTinymceDefaults(): array
     {
-        return array(
-            'advanced' => array(
-                "theme"        => "modern",
-                "plugins"      => array(
-                    "advlist autolink lists link image charmap print preview hr anchor pagebreak",
-                    "searchreplace wordcount visualblocks visualchars code fullscreen",
-                    "insertdatetime media nonbreaking save table contextmenu directionality",
-                    "emoticons template paste textcolor",
-                ),
-                "toolbar1"     => "undo redo | styleselect | bold italic | alignleft aligncenter alignright alignjustify
-                                   | bullist numlist outdent indent | link image",
-                "toolbar2"     => "print preview media | forecolor backcolor emoticons",
-                "image_advtab" => true,
-            ),
-            'simple'   => array(),
-        );
+        return [
+            'advanced' => [
+                'theme' => 'modern',
+                'plugins' => [
+                    'advlist autolink lists link image charmap print preview hr anchor pagebreak',
+                    'searchreplace wordcount visualblocks visualchars code fullscreen',
+                    'insertdatetime media nonbreaking save table contextmenu directionality',
+                    'emoticons template paste textcolor',
+                ],
+                'toolbar1' => 'undo redo | styleselect | bold italic | alignleft aligncenter alignright alignjustify
+                                   | bullist numlist outdent indent | link image',
+                'toolbar2' => 'print preview media | forecolor backcolor emoticons',
+                'image_advtab' => true,
+            ],
+            'simple' => [],
+        ];
     }
 }
diff --git a/DependencyInjection/StfalconTinymceExtension.php b/DependencyInjection/StfalconTinymceExtension.php
index ce97459b..026faa94 100644
--- a/DependencyInjection/StfalconTinymceExtension.php
+++ b/DependencyInjection/StfalconTinymceExtension.php
@@ -8,29 +8,29 @@
 use Symfony\Component\HttpKernel\DependencyInjection\Extension;
 
 /**
- * StfalconTinymceExtension
+ * StfalconTinymceExtension.
  */
 class StfalconTinymceExtension extends Extension
 {
     /**
-     * Loads the StfalconTinymce configuration.
+     * Loads the StfalconTinymceBundle configuration.
      *
      * @param array            $configs   An array of configuration values
      * @param ContainerBuilder $container A ContainerBuilder instance
      */
-    public function load(array $configs, ContainerBuilder $container)
+    public function load(array $configs, ContainerBuilder $container): void
     {
         // Get default configuration of the bundle
         $config = $this->processConfiguration(new Configuration(), $configs);
 
         if (empty($config['theme'])) {
-            $config['theme'] = array(
-                'simple' => array(),
-            );
+            $config['theme'] = [
+                'simple' => [],
+            ];
         } else {
             foreach ($config['theme'] as &$bundleTheme) {
                 // Quick fix for the removed obsolete themes
-                if (isset($bundleTheme['theme']) && in_array($bundleTheme['theme'], array('advanced', 'simple'))) {
+                if (isset($bundleTheme['theme']) && \in_array($bundleTheme['theme'], ['advanced', 'simple'], true)) {
                     $bundleTheme['theme'] = 'modern';
                 }
                 unset($bundleTheme);
@@ -51,7 +51,7 @@ public function load(array $configs, ContainerBuilder $container)
      *
      * @return string The alias
      */
-    public function getAlias()
+    public function getAlias(): string
     {
         return 'stfalcon_tinymce';
     }
diff --git a/Helper/LocaleHelper.php b/Helper/LocaleHelper.php
index 2c75f10b..e2720ef2 100644
--- a/Helper/LocaleHelper.php
+++ b/Helper/LocaleHelper.php
@@ -3,13 +3,11 @@
 namespace Stfalcon\Bundle\TinymceBundle\Helper;
 
 /**
- * Class LocaleHelper
- *
- * @package Stfalcon\Bundle\TinymceBundle\Helper
+ * LocaleHelper.
  */
 class LocaleHelper
 {
-    static private $locales = array(
+    private static $locales = [
         'bn' => 'bn_BD',
         'bg' => 'bg_BG',
         'cn' => 'zh_CN',
@@ -21,17 +19,15 @@ class LocaleHelper
         'tr' => 'tr_TR',
         'tw' => 'zh_TW',
         'uk' => 'uk_UA',
-    );
+    ];
 
     /**
      * @param string $locale
      *
      * @return string
      */
-    public static function getLanguage($locale)
+    public static function getLanguage($locale): string
     {
-        return isset(self::$locales[$locale])
-            ? self::$locales[$locale]
-            : $locale;
+        return self::$locales[$locale] ?? $locale;
     }
 }
diff --git a/Twig/Extension/StfalconTinymceExtension.php b/Twig/Extension/StfalconTinymceExtension.php
index 17d28ab7..6e18c64f 100644
--- a/Twig/Extension/StfalconTinymceExtension.php
+++ b/Twig/Extension/StfalconTinymceExtension.php
@@ -32,9 +32,8 @@ class StfalconTinymceExtension extends \Twig_Extension
     private $packages;
 
     /**
-     * Initialize tinymce helper
-     *
      * @param ContainerInterface $container
+     * @param Packages           $packages
      */
     public function __construct(ContainerInterface $container, Packages $packages)
     {
@@ -43,8 +42,6 @@ public function __construct(ContainerInterface $container, Packages $packages)
     }
 
     /**
-     * Gets a service.
-     *
      * @param string $id The service identifier
      *
      * @return object The associated service
@@ -73,13 +70,13 @@ public function getParameter($name)
      */
     public function getFunctions()
     {
-        return array(
+        return [
             'tinymce_init' => new \Twig_SimpleFunction(
                 'tinymce_init',
-                array($this, 'tinymceInit'),
-                array('is_safe' => array('html'))
+                [$this, 'tinymceInit'],
+                ['is_safe' => ['html']]
             ),
-        );
+        ];
     }
 
     /**
@@ -89,7 +86,7 @@ public function getFunctions()
      *
      * @return string
      */
-    public function tinymceInit($options = array())
+    public function tinymceInit($options = []): string
     {
         $config = $this->getParameter('stfalcon_tinymce.config');
         $config = array_merge_recursive($config, $options);
@@ -159,7 +156,7 @@ public function tinymceInit($options = array())
                 if (isset($themeOptions['content_css'])) {
                     // As there may be multiple CSS Files specified we need to parse each of them individually
                     $cssFiles = $themeOptions['content_css'];
-                    if (!is_array($themeOptions['content_css'])) {
+                    if (!\is_array($themeOptions['content_css'])) {
                         $cssFiles = explode(',', $themeOptions['content_css']);
                     }
 
@@ -173,27 +170,30 @@ public function tinymceInit($options = array())
             }
         }
 
-        $tinymceConfiguration = preg_replace(
-            array(
+        $tinymceConfiguration = \preg_replace(
+            [
                 '/"file_browser_callback":"([^"]+)"\s*/',
                 '/"file_picker_callback":"([^"]+)"\s*/',
                 '/"paste_preprocess":"([^"]+)"\s*/',
-            ),
-            array(
+            ],
+            [
                 'file_browser_callback:$1',
                 'file_picker_callback:$1',
                 '"paste_preprocess":$1',
-            ),
-            json_encode($config)
+            ],
+            \json_encode($config)
         );
 
-        return $this->getService('twig')->render('@StfalconTinymce/Script/init.html.twig', array(
-            'tinymce_config'     => $tinymceConfiguration,
-            'include_jquery'     => $config['include_jquery'],
-            'tinymce_jquery'     => $config['tinymce_jquery'],
-            'asset_package_name' => $assetPackageName,
-            'base_url'           => $this->baseUrl,
-        ));
+        return $this->getService('twig')->render(
+            '@StfalconTinymce/Script/init.html.twig',
+            [
+                'tinymce_config' => $tinymceConfiguration,
+                'include_jquery' => $config['include_jquery'],
+                'tinymce_jquery' => $config['tinymce_jquery'],
+                'asset_package_name' => $assetPackageName,
+                'base_url' => $this->baseUrl,
+            ]
+        );
     }
 
     /**
@@ -201,7 +201,7 @@ public function tinymceInit($options = array())
      *
      * @return string The extension name
      */
-    public function getName()
+    public function getName(): string
     {
         return 'stfalcon_tinymce';
     }
@@ -213,7 +213,7 @@ public function getName()
      *
      * @return string
      */
-    protected function getAssetsUrl($inputUrl)
+    protected function getAssetsUrl(string $inputUrl): string
     {
         $assets = $this->packages;
 
diff --git a/composer.json b/composer.json
index 79253240..60cad226 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
     },
     "require": {
         "php": "^7.1.3",
-        "symfony/framework-bundle": "^3.4||^4.0||^5.0"
+        "symfony/framework-bundle": "^3.4 || ^4.0"
     },
     "autoload": {
         "psr-0": {