diff --git a/src/shim.php b/src/shim.php
index 54ba2cb..620fe55 100644
--- a/src/shim.php
+++ b/src/shim.php
@@ -6,7 +6,7 @@ class_alias('PHPUnit_Framework_TestCase', 'PHPUnit'.'\Framework\TestCase');
 if (!class_exists('PHPUnit\Runner\Version')) {
     class_alias('PHPUnit_Runner_Version', 'PHPUnit\Runner\Version');
 }
-if (class_exists('PHPUnit_Framework_MockObject_Generator')) {
+if (!class_exists('PHPUnit\Framework\MockObject\Generator')) {
     class_alias('PHPUnit_Framework_MockObject_Generator', 'PHPUnit\Framework\MockObject\Generator');
     class_alias('PHPUnit_Framework_MockObject_InvocationMocker', 'PHPUnit\Framework\MockObject\InvocationMocker');
     class_alias('PHPUnit_Framework_MockObject_Invokable', 'PHPUnit\Framework\MockObject\Invokable');