diff --git a/composer.json b/composer.json
index ad0a0ca90a..559a563ea8 100644
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,6 @@
   ],
   "require": {
     "php": ">=5.6",
-    "cerdic/css-tidy": "^1.7",
     "mtdowling/cron-expression": "^1.1",
     "nesbot/carbon": "^1.21",
     "soundasleep/html2text": "dev-master",
diff --git a/composer.lock b/composer.lock
index 1249778222..e7c54b957a 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,53 +4,8 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "0029bcc47aaca4f855debb73c75e5506",
+    "content-hash": "107833c03ecbceba9b945ec28d1050d1",
     "packages": [
-        {
-            "name": "cerdic/css-tidy",
-            "version": "v1.7.1",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/Cerdic/CSSTidy.git",
-                "reference": "47bc70fc6d78a37cb91f9df4518585a9e62b565a"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/Cerdic/CSSTidy/zipball/47bc70fc6d78a37cb91f9df4518585a9e62b565a",
-                "reference": "47bc70fc6d78a37cb91f9df4518585a9e62b565a",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^5.4.0 || ^7"
-            },
-            "require-dev": {
-                "pear/text_diff": "^1.2",
-                "simpletest/simpletest": "^1.1"
-            },
-            "bin": [
-                "bin/pcsstidy"
-            ],
-            "type": "library",
-            "autoload": {
-                "classmap": [
-                    "class.csstidy_optimise.php",
-                    "class.csstidy_print.php",
-                    "class.csstidy.php"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "LGPL-2.1-or-later"
-            ],
-            "authors": [
-                {
-                    "name": "Cédric MORIN",
-                    "email": "changeme@mailinator.com"
-                }
-            ],
-            "description": "CSSTidy is a CSS minifier",
-            "time": "2019-09-14T17:59:23+00:00"
-        },
         {
             "name": "mtdowling/cron-expression",
             "version": "v1.2.1",
@@ -1523,6 +1478,7 @@
             ],
             "description": "Promoting the interoperability of container objects (DIC, SL, etc.)",
             "homepage": "https://github.com/container-interop/container-interop",
+            "abandoned": "psr/container",
             "time": "2017-02-14T19:40:03+00:00"
         },
         {
@@ -1810,12 +1766,12 @@
             "version": "v4.6.3",
             "source": {
                 "type": "git",
-                "url": "https://github.com/oscarotero/Gettext.git",
+                "url": "https://github.com/php-gettext/Gettext.git",
                 "reference": "70c6ff2fecd275e6ef9cdd542f55939a3d1904d6"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/oscarotero/Gettext/zipball/70c6ff2fecd275e6ef9cdd542f55939a3d1904d6",
+                "url": "https://api.github.com/repos/php-gettext/Gettext/zipball/70c6ff2fecd275e6ef9cdd542f55939a3d1904d6",
                 "reference": "70c6ff2fecd275e6ef9cdd542f55939a3d1904d6",
                 "shasum": ""
             },
diff --git a/lib-3rd-party/CSS.php b/lib-3rd-party/CSS.php
index f70984b4e0..6590e51575 100644
--- a/lib-3rd-party/CSS.php
+++ b/lib-3rd-party/CSS.php
@@ -1,7 +1,6 @@
 <?php
 namespace MailPoetVendor;
 
-use csstidy;
 use MailPoet\Util\pQuery\DomNode;
 use MailPoet\Util\pQuery\pQuery;
 use MailPoet\Newsletter\Renderer\EscapeHelper as EHelper;
diff --git a/lib/Config/RequirementsChecker.php b/lib/Config/RequirementsChecker.php
index 50b8b56ffe..1653ab0424 100644
--- a/lib/Config/RequirementsChecker.php
+++ b/lib/Config/RequirementsChecker.php
@@ -19,7 +19,6 @@ class RequirementsChecker {
     '\pQuery',
     '\Cron\CronExpression',
     '\Html2Text\Html2Text',
-    '\csstidy',
   ];
 
   function __construct($display_error_notice = true) {
diff --git a/lib/DI/ContainerConfigurator.php b/lib/DI/ContainerConfigurator.php
index af39d3c60b..fa7e2564c7 100644
--- a/lib/DI/ContainerConfigurator.php
+++ b/lib/DI/ContainerConfigurator.php
@@ -250,7 +250,7 @@ class ContainerConfigurator implements IContainerConfigurator {
     $container->autowire(\MailPoet\WP\Emoji::class)->setPublic(true);
     $container->autowire(\MailPoet\WP\Functions::class)->setPublic(true);
     // Third party classes
-    $container->autowire(\csstidy::class)->setClass(\csstidy::class);
+    $container->autowire(\MailPoetVendor\csstidy::class)->setClass(\MailPoetVendor\csstidy::class);
 
     return $container;
   }
diff --git a/lib/WooCommerce/TransactionalEmails/Renderer.php b/lib/WooCommerce/TransactionalEmails/Renderer.php
index 8293482287..85f93fa0c9 100644
--- a/lib/WooCommerce/TransactionalEmails/Renderer.php
+++ b/lib/WooCommerce/TransactionalEmails/Renderer.php
@@ -2,10 +2,11 @@
 
 namespace MailPoet\WooCommerce\TransactionalEmails;
 
-use csstidy;
 use MailPoet\Models\Newsletter;
 use MailPoet\Newsletter\Renderer\Preprocessor;
 use MailPoet\Newsletter\Renderer\Renderer as NewsletterRenderer;
+use MailPoetVendor\csstidy;
+use MailPoetVendor\csstidy_print;
 
 class Renderer {
   const CONTENT_CONTAINER_ID = 'mailpoet_woocommerce_container';
@@ -61,8 +62,8 @@ class Renderer {
         $this->css_parser->css[$index][$selectors] = $properties;
       }
     }
-    /** @var \csstidy_print */
+    /** @var csstidy_print */
     $print = $this->css_parser->print;
     return $print->plain();
   }
-}
\ No newline at end of file
+}
diff --git a/prefixer/composer.json b/prefixer/composer.json
index c93a674de1..031fb2ac7c 100644
--- a/prefixer/composer.json
+++ b/prefixer/composer.json
@@ -1,6 +1,7 @@
 {
   "require": {
     "php": ">=5.6",
+    "cerdic/css-tidy": "^1.7",
     "doctrine/common": "2.7.3",
     "doctrine/dbal": "2.5.13",
     "doctrine/orm": "2.5.14",
diff --git a/prefixer/composer.lock b/prefixer/composer.lock
index f3624f5758..5ef8e66f5c 100644
--- a/prefixer/composer.lock
+++ b/prefixer/composer.lock
@@ -4,8 +4,53 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "5df4d675ebafaec652b31e2e1292f695",
+    "content-hash": "3b332f4579bbf0071e8f579853b463de",
     "packages": [
+        {
+            "name": "cerdic/css-tidy",
+            "version": "v1.7.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/Cerdic/CSSTidy.git",
+                "reference": "47bc70fc6d78a37cb91f9df4518585a9e62b565a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/Cerdic/CSSTidy/zipball/47bc70fc6d78a37cb91f9df4518585a9e62b565a",
+                "reference": "47bc70fc6d78a37cb91f9df4518585a9e62b565a",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.4.0 || ^7"
+            },
+            "require-dev": {
+                "pear/text_diff": "^1.2",
+                "simpletest/simpletest": "^1.1"
+            },
+            "bin": [
+                "bin/pcsstidy"
+            ],
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "class.csstidy_optimise.php",
+                    "class.csstidy_print.php",
+                    "class.csstidy.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "LGPL-2.1-or-later"
+            ],
+            "authors": [
+                {
+                    "name": "Cédric MORIN",
+                    "email": "changeme@mailinator.com"
+                }
+            ],
+            "description": "CSSTidy is a CSS minifier",
+            "time": "2019-09-14T17:59:23+00:00"
+        },
         {
             "name": "doctrine/annotations",
             "version": "v1.4.0",
@@ -1230,7 +1275,7 @@
                 },
                 {
                     "name": "Gert de Pagter",
-                    "email": "BackEndTea@gmail.com"
+                    "email": "backendtea@gmail.com"
                 }
             ],
             "description": "Symfony polyfill for ctype functions",
diff --git a/tests/integration/WooCommerce/TransactionalEmails/RendererTest.php b/tests/integration/WooCommerce/TransactionalEmails/RendererTest.php
index 720f272c82..29b64f00cf 100644
--- a/tests/integration/WooCommerce/TransactionalEmails/RendererTest.php
+++ b/tests/integration/WooCommerce/TransactionalEmails/RendererTest.php
@@ -5,6 +5,7 @@ namespace MailPoet\WooCommerce\TransactionalEmails;
 use Codeception\Stub;
 use MailPoet\Models\Newsletter;
 use MailPoet\Newsletter\Editor\LayoutHelper as L;
+use MailPoetVendor\csstidy;
 
 class RendererTest extends \MailPoetTest {
   /** @var Newsletter */
@@ -33,7 +34,7 @@ class RendererTest extends \MailPoetTest {
   }
 
   function testGetHTMLBeforeContent() {
-    $renderer = new Renderer(new \csstidy);
+    $renderer = new Renderer(new csstidy);
     $renderer->render($this->newsletter);
     $html = $renderer->getHTMLBeforeContent('Heading Text');
     expect($html)->contains('Some text before heading');
@@ -43,7 +44,7 @@ class RendererTest extends \MailPoetTest {
   }
 
   function testGetHTMLAfterContent() {
-    $renderer = new Renderer(new \csstidy);
+    $renderer = new Renderer(new csstidy);
     $renderer->render($this->newsletter);
     $html = $renderer->getHTMLAfterContent('Heading Text');
     expect($html)->notContains('Some text before heading');
@@ -53,7 +54,7 @@ class RendererTest extends \MailPoetTest {
   }
 
   function testPrefixCss() {
-    $renderer = new Renderer(new \csstidy);
+    $renderer = new Renderer(new csstidy);
     $css = $renderer->prefixCss('
       #some_id {color: black}
       .some-class {height: 50px; width: 30px}