diff --git a/.atoum.php b/.atoum.php
index 15ce53f..2e1122f 100644
--- a/.atoum.php
+++ b/.atoum.php
@@ -2,7 +2,7 @@
 
 include 'vendor/autoload.php';
 
-use mageekguy\atoum;
+use atoum\atoum;
 use Symfony\Component\Debug\ErrorHandler;
 use Symfony\Component\Debug\ExceptionHandler;
 
diff --git a/.travis.yml b/.travis.yml
index 788e635..0df959d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,11 +1,12 @@
 language: php
-dist: trusty
+dist: bionic
 
 php:
-  - 5.6
-  - 7.0
-  - 7.1
   - 7.2
+  - 7.3
+  - 7.4
+  - 8.0
+  - 8.1
 
 env:
   global:
@@ -26,10 +27,11 @@ before_script:
 script:
   # Reset CUPS and PDF Printer
   - sudo apt-get remove -yqq cups cups-pdf
-  - sudo apt-get install -yqq cups cups-pdf
+  - sudo apt-get install -yqq cups cups-pdf cups-client
   - sudo adduser travis lpadmin
   - sudo service cups restart
   # Test PDF Printer
+  - which lp
   - lp -d PDF LICENSE && sleep 10
   # Run Tests
   - ./vendor/bin/atoum -d tests/ -ncc -utr
diff --git a/composer.json b/composer.json
index 57053ba..94578c4 100644
--- a/composer.json
+++ b/composer.json
@@ -10,16 +10,16 @@
         }
     ],
     "require": {
-        "php": ">=5.6",
-        "php-http/socket-client": "*",
-        "php-http/client-common": "*",
-        "php-http/message": "*",
-        "guzzlehttp/psr7": "*",
-        "symfony/yaml": "*"
+        "php": ">=7.2",
+        "php-http/socket-client": "^2.1",
+        "php-http/client-common": "^2.6",
+        "php-http/message": "^1.13",
+        "guzzlehttp/psr7": "^1.9",
+        "symfony/yaml": "^4.4||^5.4"
     },
     "require-dev": {
-        "symfony/debug": "*",
-        "atoum/atoum": "*"
+        "symfony/debug": "^4.4||^5.4",
+        "atoum/atoum": "^4.0"
     },
     "minimum-stability": "dev",
     "prefer-stable": true,
diff --git a/src/Transport/Client.php b/src/Transport/Client.php
index 27218f2..ff12d5c 100644
--- a/src/Transport/Client.php
+++ b/src/Transport/Client.php
@@ -12,6 +12,7 @@
 use Http\Client\Socket\Client as SocketHttpClient;
 use Http\Message\MessageFactory\GuzzleMessageFactory;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 use Smalot\Cups\CupsException;
 
 /**
@@ -116,7 +117,7 @@ public function setAuthType($authType)
     /**
      * (@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         if ($this->username || $this->password) {
             switch ($this->authType) {
diff --git a/tests/Builder/Builder.php b/tests/Builder/Builder.php
index 3aae968..387022d 100644
--- a/tests/Builder/Builder.php
+++ b/tests/Builder/Builder.php
@@ -2,7 +2,7 @@
 
 namespace Smalot\Cups\Tests\Units\Builder;
 
-use mageekguy\atoum;
+use atoum\atoum;
 use Smalot\Cups\Model\Job;
 use Smalot\Cups\Model\Printer;
 use Smalot\Cups\Transport\Client;
diff --git a/tests/Manager/JobManager.php b/tests/Manager/JobManager.php
index 95772da..173ab96 100644
--- a/tests/Manager/JobManager.php
+++ b/tests/Manager/JobManager.php
@@ -2,7 +2,7 @@
 
 namespace Smalot\Cups\Tests\Units\Manager;
 
-use mageekguy\atoum;
+use atoum\atoum;
 use Smalot\Cups\Builder\Builder;
 use Smalot\Cups\Model\Job;
 use Smalot\Cups\Model\Printer;
diff --git a/tests/Manager/PrinterManager.php b/tests/Manager/PrinterManager.php
index 4d86c49..56e120b 100644
--- a/tests/Manager/PrinterManager.php
+++ b/tests/Manager/PrinterManager.php
@@ -2,7 +2,7 @@
 
 namespace Smalot\Cups\Tests\Units\Manager;
 
-use mageekguy\atoum;
+use atoum\atoum;
 use Smalot\Cups\Builder\Builder;
 use Smalot\Cups\Model\Printer;
 use Smalot\Cups\Model\PrinterInterface;
diff --git a/tests/Model/Job.php b/tests/Model/Job.php
index fff60bb..0ebbc13 100644
--- a/tests/Model/Job.php
+++ b/tests/Model/Job.php
@@ -2,7 +2,7 @@
 
 namespace Smalot\Cups\Tests\Units\Model;
 
-use mageekguy\atoum;
+use atoum\atoum;
 
 /**
  * Class Job
diff --git a/tests/Model/Printer.php b/tests/Model/Printer.php
index 32729b9..2a78fa3 100644
--- a/tests/Model/Printer.php
+++ b/tests/Model/Printer.php
@@ -2,7 +2,7 @@
 
 namespace Smalot\Cups\Tests\Units\Model;
 
-use mageekguy\atoum;
+use atoum\atoum;
 
 /**
  * Class Printer
diff --git a/tests/Transport/Client.php b/tests/Transport/Client.php
index 67270f3..48c6142 100644
--- a/tests/Transport/Client.php
+++ b/tests/Transport/Client.php
@@ -3,6 +3,7 @@
 namespace Smalot\Cups\Tests\Units\Transport;
 
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 use Smalot\Cups\Transport\Client as BaseClient;
 
 /**
@@ -26,7 +27,7 @@ class Client extends BaseClient
     /**
      * @inheritDoc
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         $this->lastRequest = $request;
         $this->lastResponse = parent::sendRequest($request);