diff --git a/src/TestCase.php b/src/TestCase.php
index c249afc..2097f9d 100644
--- a/src/TestCase.php
+++ b/src/TestCase.php
@@ -2,6 +2,8 @@
 
 namespace Omnipay\Tests;
 
+use Http\Discovery\HttpClientDiscovery;
+use Http\Discovery\Strategy\MockClientStrategy;
 use Mockery as m;
 use Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;
 use Omnipay\Common\Http\Client;
@@ -34,6 +36,13 @@ abstract class TestCase extends PHPUnitTestCase
     /** @var HttpRequest */
     private $httpRequest;
 
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        HttpClientDiscovery::prependStrategy(MockClientStrategy::class);
+    }
+
     /**
      * Converts a string to camel case
      *