diff --git a/ChangeLog-5.7.md b/ChangeLog-5.7.md
index bdd0723c6a5..dd4e4bc25b3 100644
--- a/ChangeLog-5.7.md
+++ b/ChangeLog-5.7.md
@@ -7,6 +7,8 @@ All notable changes of the PHPUnit 5.7 release series are documented in this fil
 ### Fixed
 
 * Fixed [#2236](https://github.com/sebastianbergmann/phpunit/issues/2236): Exceptions in `tearDown()` do not affect `getStatus()`
+* Fixed [#2950](https://github.com/sebastianbergmann/phpunit/issues/2950): Class extending `PHPUnit\Framework\TestSuite` does not extend `PHPUnit\FrameworkTestCase`
+* Fixed [#2972](https://github.com/sebastianbergmann/phpunit/issues/2972): PHPUnit crashes when test suite contains both `.phpt` files and unconventionally named tests
 
 ## [5.7.26] - 2017-12-17
 
diff --git a/ChangeLog-6.5.md b/ChangeLog-6.5.md
index f8ae36fd2ec..6ff08c06bf5 100644
--- a/ChangeLog-6.5.md
+++ b/ChangeLog-6.5.md
@@ -7,6 +7,8 @@ All notable changes of the PHPUnit 6.5 release series are documented in this fil
 ### Fixed
 
 * Fixed [#2236](https://github.com/sebastianbergmann/phpunit/issues/2236): Exceptions in `tearDown()` do not affect `getStatus()`
+* Fixed [#2950](https://github.com/sebastianbergmann/phpunit/issues/2950): Class extending `PHPUnit\Framework\TestSuite` does not extend `PHPUnit\FrameworkTestCase`
+* Fixed [#2972](https://github.com/sebastianbergmann/phpunit/issues/2972): PHPUnit crashes when test suite contains both `.phpt` files and unconventionally named tests
 
 ## [6.5.5] - 2017-12-17
 
diff --git a/src/Framework/TestSuite.php b/src/Framework/TestSuite.php
index ed70f5566ed..21a43596ed4 100644
--- a/src/Framework/TestSuite.php
+++ b/src/Framework/TestSuite.php
@@ -305,7 +305,7 @@ public function addTestSuite($testClass): void
                 }
             }
 
-            if (!$suiteMethod && !$testClass->isAbstract()) {
+            if (!$suiteMethod && !$testClass->isAbstract() && $testClass->isSubclassOf(TestCase::class)) {
                 $this->addTest(new self($testClass));
             }
         } else {
diff --git a/tests/Regression/GitHub/2972.phpt b/tests/Regression/GitHub/2972.phpt
new file mode 100644
index 00000000000..db9e56963dc
--- /dev/null
+++ b/tests/Regression/GitHub/2972.phpt
@@ -0,0 +1,18 @@
+--TEST--
+GH-2972: Test suite shouldn't fail when it contains both *.phpt files and unconventionally named tests
+--FILE--
+<?php
+$_SERVER['argv'][1] = '--no-configuration';
+$_SERVER['argv'][2] = __DIR__ . '/2972/';
+
+require __DIR__ . '/../../bootstrap.php';
+PHPUnit\TextUI\Command::main();
+?>
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+..                                                                  2 / 2 (100%)
+
+Time: %s, Memory: %s
+
+OK (2 tests, 2 assertions)
diff --git a/tests/Regression/GitHub/2972/issue-2972-test.phpt b/tests/Regression/GitHub/2972/issue-2972-test.phpt
new file mode 100644
index 00000000000..4d09cf5a94e
--- /dev/null
+++ b/tests/Regression/GitHub/2972/issue-2972-test.phpt
@@ -0,0 +1,10 @@
+--TEST--
+Just a sample test for issue 2972, does not actually test anything
+--FILE--
+<?php
+echo "Hello world\n";
+?>
+===DONE===
+--EXPECT--
+Hello world
+===DONE===
diff --git a/tests/Regression/GitHub/2972/unconventiallyNamedIssue2972Test.php b/tests/Regression/GitHub/2972/unconventiallyNamedIssue2972Test.php
new file mode 100644
index 00000000000..3fd57f018ec
--- /dev/null
+++ b/tests/Regression/GitHub/2972/unconventiallyNamedIssue2972Test.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Issue2972;
+
+use PHPUnit\Framework\TestCase;
+
+class Issue2972Test extends TestCase
+{
+    public function testHello()
+    {
+        $this->assertNotEmpty('Hello world!');
+    }
+}