diff --git a/README.md b/README.md
index 4ade7ed5..9d746415 100644
--- a/README.md
+++ b/README.md
@@ -19,10 +19,11 @@ It is based on a lot of great frameworks. Special thanks to [Symfony v4](https:/
 ### Requirements
 
 - PHP 7.1.3 or higher
-- One PHP extension of PDO-SQLite or PDO-MySQL enabled (it might work with PostgreSQL and Oracle as well, but that wasn't tested and is not officially supported)
+- One PHP extension of [PDO-SQLite](https://php.net/manual/en/ref.pdo-sqlite.php) or [PDO-MySQL](https://php.net/manual/en/ref.pdo-mysql.php) enabled (it might work with PostgreSQL and Oracle as well, but that wasn't tested and is not officially supported)
+- The PHP extension [intl](https://php.net/manual/en/book.intl.php)
 - the [usual Symfony application requirements](http://symfony.com/doc/current/reference/requirements.html)
 - Kimai needs to be installed in the root directory of a domain or you need to [recompile the frontend assets](var/docs/developers.md)
-- a modern browser, Kimai v2 might be broken on old browsers like the IE 9
+- a modern browser, Kimai v2 might be broken on old browsers like IE 9
 
 ## Documentation & Roadmap
 
diff --git a/composer.json b/composer.json
index c82c3529..2aeb72af 100644
--- a/composer.json
+++ b/composer.json
@@ -5,7 +5,9 @@
     "description": "Kimai Time-Tracking 2",
     "require": {
         "php": "^7.1.3",
+        "ext-pdo": "*",
         "ext-pdo_sqlite": "*",
+        "ext-intl": "*",
         "avanzu/admin-theme-bundle": "dev-kevinpapst",
         "beberlei/DoctrineExtensions": "^1.0",
         "erusev/parsedown": "^1.6",
@@ -25,7 +27,6 @@
         "symfony/security-bundle": "^4.0",
         "symfony/security-csrf": "^4.0",
         "symfony/swiftmailer-bundle": "^3.1",
-        "symfony/thanks": "^1.0",
         "symfony/translation": "^4.0",
         "symfony/twig-bundle": "^4.0",
         "symfony/validator": "^4.0",
@@ -45,6 +46,7 @@
         "symfony/debug-pack": "^1.0",
         "symfony/maker-bundle": "^1.0",
         "symfony/phpunit-bridge": "^4.0",
+        "symfony/thanks": "^1.0",
         "symfony/web-server-bundle": "^4.0"
     },
     "config": {
diff --git a/composer.lock b/composer.lock
index 0224ffc2..f739000b 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "3ae4c225619897f7feb4f4e99da7bf01",
+    "content-hash": "91e4b63b85862338cd5c14989b384afa",
     "packages": [
         {
             "name": "almasaeed2010/adminlte",
@@ -4094,49 +4094,6 @@
             "homepage": "http://symfony.com",
             "time": "2018-04-03T16:29:41+00:00"
         },
-        {
-            "name": "symfony/thanks",
-            "version": "v1.0.7",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/symfony/thanks.git",
-                "reference": "bade4992c46ed722162694b4af8d72f84402819a"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/thanks/zipball/bade4992c46ed722162694b4af8d72f84402819a",
-                "reference": "bade4992c46ed722162694b4af8d72f84402819a",
-                "shasum": ""
-            },
-            "require": {
-                "composer-plugin-api": "^1.0",
-                "php": "^5.5.9|^7.0.0"
-            },
-            "type": "composer-plugin",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.0-dev"
-                },
-                "class": "Symfony\\Thanks\\Thanks"
-            },
-            "autoload": {
-                "psr-4": {
-                    "Symfony\\Thanks\\": "src"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Nicolas Grekas",
-                    "email": "p@tchwork.com"
-                }
-            ],
-            "description": "Give thanks (in the form of a GitHub ⭐) to your fellow PHP package maintainers (not limited to Symfony components)!",
-            "time": "2018-03-14T21:51:39+00:00"
-        },
         {
             "name": "symfony/translation",
             "version": "v4.1.1",
@@ -7206,6 +7163,49 @@
             "homepage": "https://symfony.com",
             "time": "2018-06-11T12:56:28+00:00"
         },
+        {
+            "name": "symfony/thanks",
+            "version": "v1.0.7",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/thanks.git",
+                "reference": "bade4992c46ed722162694b4af8d72f84402819a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/thanks/zipball/bade4992c46ed722162694b4af8d72f84402819a",
+                "reference": "bade4992c46ed722162694b4af8d72f84402819a",
+                "shasum": ""
+            },
+            "require": {
+                "composer-plugin-api": "^1.0",
+                "php": "^5.5.9|^7.0.0"
+            },
+            "type": "composer-plugin",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0-dev"
+                },
+                "class": "Symfony\\Thanks\\Thanks"
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Thanks\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                }
+            ],
+            "description": "Give thanks (in the form of a GitHub ⭐) to your fellow PHP package maintainers (not limited to Symfony components)!",
+            "time": "2018-03-14T21:51:39+00:00"
+        },
         {
             "name": "symfony/web-server-bundle",
             "version": "v4.1.1",
@@ -7366,7 +7366,9 @@
     "prefer-lowest": false,
     "platform": {
         "php": "^7.1.3",
-        "ext-pdo_sqlite": "*"
+        "ext-pdo": "*",
+        "ext-pdo_sqlite": "*",
+        "ext-intl": "*"
     },
     "platform-dev": []
 }
diff --git a/symfony.lock b/symfony.lock
index aa7820a9..c2e00eb6 100644
--- a/symfony.lock
+++ b/symfony.lock
@@ -432,7 +432,7 @@
         }
     },
     "symfony/thanks": {
-        "version": "v1.0.1"
+        "version": "v1.0.7"
     },
     "symfony/translation": {
         "version": "3.3",