diff --git a/src/Kernel.php b/src/Kernel.php
index 5e34b6a5..81d01b1d 100644
--- a/src/Kernel.php
+++ b/src/Kernel.php
@@ -20,8 +20,6 @@ final class Kernel
 
     private const EXCEPTION_EXIT = 2;
 
-    private const CRASH_EXIT = 255;
-
     /**
      * The Kernel bootstrappers.
      *
@@ -112,7 +110,7 @@ final class Kernel
                 + $result->numberOfTestsWithTestTriggeredWarningEvents()
                 + $result->numberOfTestsWithTestTriggeredPhpWarningEvents();
 
-            if ($configuration->failOnWarning() && ! empty($warnings)) {
+            if ($configuration->failOnWarning() && $warnings > 0) {
                 $returnCode = self::FAILURE_EXIT;
             }
 
diff --git a/src/TestCases/IgnorableTest.php b/src/TestCases/IgnorableTest.php
index 812e90d4..311acbc1 100644
--- a/src/TestCases/IgnorableTest.php
+++ b/src/TestCases/IgnorableTest.php
@@ -9,7 +9,7 @@ use PHPUnit\Framework\TestCase;
 /**
  * @internal
  */
-class IgnorableTest extends TestCase
+final class IgnorableTest extends TestCase
 {
-
+    // ..
 }