diff --git a/.travis.yml b/.travis.yml
index bcfcdeb..7111012 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,10 @@ php:
   - 7.0
   - 7.1
   - 7.2
+  - 7.3
+  - 7.4
+  - 8.0
+  - 8.1
 
 before_script:
   - composer install -n --dev --prefer-source
diff --git a/composer.json b/composer.json
index 8f11756..eb17311 100644
--- a/composer.json
+++ b/composer.json
@@ -18,13 +18,13 @@
     }
   },
   "require": {
-    "php": "^7.0|^7.1|^7.2|^7.3|^7.4",
+    "php": "^7.0|^8.0",
     "ext-simplexml": "*",
     "ext-dom": "*",
-    "omnipay/common": "^3.0"
+    "omnipay/common": "^3.2"
   },
   "require-dev": {
-    "omnipay/tests": "^3.0",
+    "omnipay/tests": "^4.1",
     "satooshi/php-coveralls": "1.0.0",
     "guzzlehttp/guzzle": "^6.5.5",
     "squizlabs/php_codesniffer": "3.*"
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 1ecb290..5692c91 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -9,6 +9,9 @@
          processIsolation="false"
          stopOnFailure="false"
          syntaxCheck="false">
+    <php>
+        <ini name="error_reporting" value="E_ALL &amp; ~E_DEPRECATED"/>
+    </php>
     <testsuites>
         <testsuite name="WebMoney Test Suite">
             <directory>./tests/</directory>
diff --git a/src/Message/PayoutRequest.php b/src/Message/PayoutRequest.php
index 5749744..05763a1 100644
--- a/src/Message/PayoutRequest.php
+++ b/src/Message/PayoutRequest.php
@@ -279,7 +279,7 @@ public function getData()
     /**
      * @return Client
      */
-    private function getHttpClient()
+    protected function getHttpClient()
     {
         return new Client($this->endpoint);
     }
diff --git a/tests/GatewayTest.php b/tests/GatewayTest.php
index 47785e5..ed5937a 100644
--- a/tests/GatewayTest.php
+++ b/tests/GatewayTest.php
@@ -9,7 +9,7 @@ class GatewayTest extends GatewayTestCase
     public $sslFile;
     public $sslKey;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/CompletePurchaseRequestTest.php b/tests/Message/CompletePurchaseRequestTest.php
index e97c87f..83b8423 100644
--- a/tests/Message/CompletePurchaseRequestTest.php
+++ b/tests/Message/CompletePurchaseRequestTest.php
@@ -9,7 +9,7 @@ class CompletePurchaseRequestTest extends TestCase
 {
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/CompletePurchaseResponseTest.php b/tests/Message/CompletePurchaseResponseTest.php
index 1f0fe1d..74d5f3b 100644
--- a/tests/Message/CompletePurchaseResponseTest.php
+++ b/tests/Message/CompletePurchaseResponseTest.php
@@ -9,7 +9,7 @@ class CompletePurchaseResponseTest extends TestCase
 {
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/FetchTransactionRequestTest.php b/tests/Message/FetchTransactionRequestTest.php
index d13f3ae..e5c3f36 100644
--- a/tests/Message/FetchTransactionRequestTest.php
+++ b/tests/Message/FetchTransactionRequestTest.php
@@ -8,7 +8,7 @@ class FetchTransactionRequestTest extends TestCase
 {
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/FetchTransactionResponseTest.php b/tests/Message/FetchTransactionResponseTest.php
index 7bc6465..2d1449b 100644
--- a/tests/Message/FetchTransactionResponseTest.php
+++ b/tests/Message/FetchTransactionResponseTest.php
@@ -9,7 +9,7 @@ class FetchTransactionResponseTest extends TestCase
 
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/PayoutRequestTest.php b/tests/Message/PayoutRequestTest.php
index 39ee8aa..d81324d 100644
--- a/tests/Message/PayoutRequestTest.php
+++ b/tests/Message/PayoutRequestTest.php
@@ -12,7 +12,7 @@ class PayoutRequestTest extends TestCase
 {
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
@@ -28,7 +28,7 @@ public function setUp()
         $httpClient->addSubscriber($mockPlugin);
 
         $this->request = $this->getMockBuilder(PayoutRequest::class)
-            ->setMethods(['getHttpClient'])
+            ->onlyMethods(['getHttpClient'])
             ->setConstructorArgs([$this->getHttpClient(), $this->getHttpRequest()])
             ->getMock();
 
diff --git a/tests/Message/PayoutResponseTest.php b/tests/Message/PayoutResponseTest.php
index a39696f..308cf8e 100644
--- a/tests/Message/PayoutResponseTest.php
+++ b/tests/Message/PayoutResponseTest.php
@@ -9,7 +9,7 @@ class PayoutResponseTest extends TestCase
 
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/PurchaseRequestTest.php b/tests/Message/PurchaseRequestTest.php
index 6c24d1f..388a012 100644
--- a/tests/Message/PurchaseRequestTest.php
+++ b/tests/Message/PurchaseRequestTest.php
@@ -9,7 +9,7 @@ class PurchaseRequestTest extends TestCase
 {
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/PurchaseResponseTest.php b/tests/Message/PurchaseResponseTest.php
index 47e2b1c..e38e576 100644
--- a/tests/Message/PurchaseResponseTest.php
+++ b/tests/Message/PurchaseResponseTest.php
@@ -8,7 +8,7 @@ class PurchaseResponseTest extends TestCase
 {
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();