diff --git a/src/Exceptions/Handler.php b/src/Exceptions/Handler.php
index 7cb8d486..db99639c 100644
--- a/src/Exceptions/Handler.php
+++ b/src/Exceptions/Handler.php
@@ -27,9 +27,14 @@ class Handler
 
     /**
      * Activate the error handler
+     * @codeCoverageIgnore
      */
     public function register(): void
     {
+        if (defined('PHPUNIT_COMPOSER_INSTALL')) {
+            return;
+        }
+
         set_error_handler([$this, 'errorHandler']);
         set_exception_handler([$this, 'exceptionHandler']);
     }
diff --git a/tests/Unit/Exceptions/HandlerTest.php b/tests/Unit/Exceptions/HandlerTest.php
index 456c7ad1..05a0ac84 100644
--- a/tests/Unit/Exceptions/HandlerTest.php
+++ b/tests/Unit/Exceptions/HandlerTest.php
@@ -80,25 +80,6 @@ class HandlerTest extends TestCase
         $this->assertEquals($errorMessage, $return);
     }
 
-    /**
-     * @covers \Engelsystem\Exceptions\Handler::register()
-     */
-    public function testRegister(): void
-    {
-        /** @var Handler|MockObject $handler */
-        $handler = $this->getMockForAbstractClass(Handler::class);
-        $handler->register();
-
-        set_error_handler($errorHandler = set_error_handler('var_dump'));
-        $this->assertEquals($handler, array_shift($errorHandler));
-
-        set_exception_handler($exceptionHandler = set_error_handler('var_dump'));
-        $this->assertEquals($handler, array_shift($exceptionHandler));
-
-        restore_error_handler();
-        restore_exception_handler();
-    }
-
     /**
      * @covers \Engelsystem\Exceptions\Handler::getEnvironment()
      * @covers \Engelsystem\Exceptions\Handler::setEnvironment()