diff --git a/ChangeLog-9.5.md b/ChangeLog-9.5.md
index 263d9023e04..2646df236a3 100644
--- a/ChangeLog-9.5.md
+++ b/ChangeLog-9.5.md
@@ -4,4 +4,8 @@ All notable changes of the PHPUnit 9.5 release series are documented in this fil
 
 ## [9.5.0] - 2020-12-04
 
+### Changed
+
+* [#4490](https://github.com/sebastianbergmann/phpunit/issues/4490): Emit Error instead of Warning when test case class cannot be instantiated
+
 [9.5.0]: https://github.com/sebastianbergmann/phpunit/compare/9.4...master
diff --git a/src/Framework/TestBuilder.php b/src/Framework/TestBuilder.php
index 583a9f2c485..92a57d02f8d 100644
--- a/src/Framework/TestBuilder.php
+++ b/src/Framework/TestBuilder.php
@@ -30,7 +30,7 @@ public function build(ReflectionClass $theClass, string $methodName): Test
         $className = $theClass->getName();
 
         if (!$theClass->isInstantiable()) {
-            return new WarningTestCase(
+            return new ErrorTestCase(
                 sprintf('Cannot instantiate class "%s".', $className)
             );
         }
diff --git a/tests/unit/Framework/TestBuilderTest.php b/tests/unit/Framework/TestBuilderTest.php
index ae962074555..c3846c9d0da 100644
--- a/tests/unit/Framework/TestBuilderTest.php
+++ b/tests/unit/Framework/TestBuilderTest.php
@@ -66,8 +66,10 @@ public function testCreateTestForNotInstantiableTestClass(): void
             ->willReturn('foo');
 
         $test = (new TestBuilder)->build($reflector, 'TestForNonInstantiableTestClass');
-        $this->assertInstanceOf(WarningTestCase::class, $test);
-        /* @var WarningTestCase $test */
+
+        $this->assertInstanceOf(ErrorTestCase::class, $test);
+
+        /* @var ErrorTestCase $test */
         $this->assertSame('Cannot instantiate class "foo".', $test->getMessage());
     }