diff --git a/README.md b/README.md
index 3e37027..7425e2d 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 Lendable PHPUnit Extensions
-========================
+===========================
 
 > [!WARNING]
 > This library is still in early development.
diff --git a/composer.json b/composer.json
index 499feaa..bc315d0 100644
--- a/composer.json
+++ b/composer.json
@@ -32,6 +32,7 @@
     "autoload-dev": {
         "psr-4": {
             "Tests\\Fixtures\\Lendable\\PHPUnitExtensions\\": "tests/fixtures/",
+            "Tests\\Phpstan\\Lendable\\PHPUnitExtensions\\": "tests/phpstan/",
             "Tests\\Unit\\Lendable\\PHPUnitExtensions\\": "tests/unit/"
         }
     },
@@ -61,6 +62,9 @@
         "phpstan": [
             "phpstan analyse --ansi --no-progress --memory-limit=-1"
         ],
+        "phpunit:phpstan": [
+            "phpunit --colors --testsuite=phpstan"
+        ],
         "phpunit:unit": [
             "phpunit --colors --testsuite=unit"
         ],
@@ -77,7 +81,8 @@
             "@rector:check"
         ],
         "tests": [
-            "@tests:unit"
+            "@tests:unit",
+            "@phpunit:phpstan"
         ],
         "tests:unit": [
             "@phpunit:unit"
diff --git a/phpstan.neon b/phpstan.neon
index b87a965..001b146 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -3,6 +3,7 @@ includes:
   - vendor/phpstan/phpstan-deprecation-rules/rules.neon
   - vendor/phpstan/phpstan-strict-rules/rules.neon
   - phar://vendor/phpstan/phpstan/phpstan.phar/conf/bleedingEdge.neon
+  - phpstan/rules.neon
 
 parameters:
   tmpDir: tmp/phpstan
@@ -11,3 +12,9 @@ parameters:
     - tests
   level: max
   checkExplicitMixed: true
+  excludePaths:
+    - %currentWorkingDirectory%/tests/phpstan
+  lendable_phpunit:
+    enforceStrictMocking:
+      pardoned:
+        - Tests\Unit\Lendable\PHPUnitExtensions\TestCaseTest
diff --git a/phpstan/rules.neon b/phpstan/rules.neon
new file mode 100644
index 0000000..9d15959
--- /dev/null
+++ b/phpstan/rules.neon
@@ -0,0 +1,23 @@
+conditionalTags:
+  Lendable\PHPUnitExtensions\Phpstan\Rule\EnforceStrictMocking:
+    phpstan.rules.rule: %lendable_phpunit.enforceStrictMocking.enabled%
+
+parametersSchema:
+  lendable_phpunit: structure([
+    enforceStrictMocking: structure([
+      enabled: bool()
+      pardoned: listOf(string())
+    ])
+  ])
+
+parameters:
+  lendable_phpunit:
+    enforceStrictMocking:
+      enabled: true
+      pardoned: []
+
+services:
+  -
+    class: Lendable\PHPUnitExtensions\Phpstan\Rule\EnforceStrictMocking
+    arguments:
+      pardoned: %lendable_phpunit.enforceStrictMocking.pardoned%
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 3ca1769..bd3b7e1 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -17,5 +17,9 @@
         <testsuite name="unit">
             <directory>./tests/unit/</directory>
         </testsuite>
+        <testsuite name="phpstan">
+            <directory>./tests/phpstan/</directory>
+            <exclude>./tests/phpstan/data/</exclude>
+        </testsuite>
     </testsuites>
 </phpunit>
diff --git a/src/Phpstan/Rule/EnforceStrictMocking.php b/src/Phpstan/Rule/EnforceStrictMocking.php
new file mode 100644
index 0000000..5742a5d
--- /dev/null
+++ b/src/Phpstan/Rule/EnforceStrictMocking.php
@@ -0,0 +1,91 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Lendable\PHPUnitExtensions\Phpstan\Rule;
+
+use Lendable\PHPUnitExtensions\StrictMocking as StrictMockingTrait;
+use Lendable\PHPUnitExtensions\TestCase as StrictMockingTestCase;
+use PhpParser\Node;
+use PhpParser\Node\Name;
+use PhpParser\Node\Stmt\Class_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @implements Rule<Class_>
+ */
+final class EnforceStrictMocking implements Rule
+{
+    /**
+     * @var array<class-string, int>
+     */
+    private readonly array $pardoned;
+
+    /**
+     * @param list<class-string> $pardoned
+     */
+    public function __construct(array $pardoned)
+    {
+        $this->pardoned = \array_flip($pardoned);
+    }
+
+    public function getNodeType(): string
+    {
+        return Class_::class;
+    }
+
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if (!$node->namespacedName instanceof Name) {
+            return [];
+        }
+
+        if (!$node->extends instanceof Name) {
+            return [];
+        }
+
+        if ($node->isAbstract()) {
+            return [];
+        }
+
+        $className = $node->namespacedName->toString();
+        if (!\str_ends_with($className, 'Test')) {
+            return [];
+        }
+
+        if (isset($this->pardoned[$className])) {
+            return [];
+        }
+
+        $reflection = $scope->resolveTypeByName($node->namespacedName)->getClassReflection();
+        if (!$reflection instanceof ClassReflection) {
+            return [];
+        }
+
+        $parents = $reflection->getParentClassesNames();
+        if (!\in_array(TestCase::class, $parents, true)) {
+            return [];
+        }
+
+        if (\in_array(StrictMockingTestCase::class, $parents, true)) {
+            return [];
+        }
+
+        if (isset($reflection->getTraits(true)[StrictMockingTrait::class])) {
+            return [];
+        }
+
+        $ruleErrorBuilder = RuleErrorBuilder::message(\sprintf(
+            'Class "%s" must either extend "%s" or use "%s" trait.',
+            $className,
+            StrictMockingTestCase::class,
+            StrictMockingTrait::class,
+        ));
+
+        return [$ruleErrorBuilder->build()];
+    }
+}
diff --git a/tests/phpstan/Rule/EnforceExtendedClassTest.php b/tests/phpstan/Rule/EnforceExtendedClassTest.php
new file mode 100644
index 0000000..8a7d2df
--- /dev/null
+++ b/tests/phpstan/Rule/EnforceExtendedClassTest.php
@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\Rule;
+
+use Lendable\PHPUnitExtensions\Phpstan\Rule\EnforceStrictMocking;
+use Lendable\PHPUnitExtensions\StrictMocking;
+use Lendable\PHPUnitExtensions\TestCase;
+use PHPStan\Testing\RuleTestCase;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Test;
+use Tests\Phpstan\Lendable\PHPUnitExtensions\data\IndirectlyExtendingTest;
+use Tests\Phpstan\Lendable\PHPUnitExtensions\data\TestCaseTest;
+
+#[CoversClass(EnforceStrictMocking::class)]
+final class EnforceExtendedClassTest extends RuleTestCase
+{
+    #[Test]
+    public function reports_test_directly_extending_phpunits_test_case(): void
+    {
+        $this->analyse([__DIR__.'/../data/TestCaseTest.php'], [
+            [
+                $this->errorMessageFor(TestCaseTest::class),
+                9,
+            ],
+        ]);
+    }
+
+    #[Test]
+    public function does_not_report_abstract_test_directly_extending_phpunits_test_case(): void
+    {
+        $this->analyse([__DIR__.'/../data/AbstractTestCaseTest.php'], []);
+    }
+
+    #[Test]
+    public function reports_test_indirectly_extending_phpunits_test_case(): void
+    {
+        $this->analyse([__DIR__.'/../data/IndirectlyExtendingTest.php'], [
+            [
+                $this->errorMessageFor(IndirectlyExtendingTest::class),
+                7,
+            ],
+        ]);
+    }
+
+    #[Test]
+    public function does_not_report_test_extending_strict_mocking(): void
+    {
+        $this->analyse([__DIR__.'/../data/StrictMockingTestCaseTest.php'], []);
+    }
+
+    #[Test]
+    public function does_not_report_test_directly_using_strict_mocking_trait(): void
+    {
+        $this->analyse([__DIR__.'/../data/StrictMockingTraitTest.php'], []);
+    }
+
+    #[Test]
+    public function does_not_report_test_indirectly_using_strict_mocking_trait(): void
+    {
+        $this->analyse([__DIR__.'/../data/IndirectStrictMockingTraitTest.php'], []);
+    }
+
+    protected function getRule(): EnforceStrictMocking
+    {
+        return new EnforceStrictMocking([]);
+    }
+
+    private function errorMessageFor(string $class): string
+    {
+        return \sprintf(
+            'Class "%s" must either extend "%s" or use "%s" trait.',
+            $class,
+            TestCase::class,
+            StrictMocking::class,
+        );
+    }
+}
diff --git a/tests/phpstan/data/AbstractTestCaseTest.php b/tests/phpstan/data/AbstractTestCaseTest.php
new file mode 100644
index 0000000..e4ab258
--- /dev/null
+++ b/tests/phpstan/data/AbstractTestCaseTest.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\data;
+
+use PHPUnit\Framework\TestCase;
+
+abstract class AbstractTestCaseTest extends TestCase {}
diff --git a/tests/phpstan/data/IndirectStrictMockingTraitTest.php b/tests/phpstan/data/IndirectStrictMockingTraitTest.php
new file mode 100644
index 0000000..fdcf8fc
--- /dev/null
+++ b/tests/phpstan/data/IndirectStrictMockingTraitTest.php
@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\data;
+
+final class IndirectStrictMockingTraitTest extends StrictMockingTraitTest {}
diff --git a/tests/phpstan/data/IndirectlyExtendingTest.php b/tests/phpstan/data/IndirectlyExtendingTest.php
new file mode 100644
index 0000000..f6eaf90
--- /dev/null
+++ b/tests/phpstan/data/IndirectlyExtendingTest.php
@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\data;
+
+class IndirectlyExtendingTest extends TestCaseTest {}
diff --git a/tests/phpstan/data/StrictMockingTestCaseTest.php b/tests/phpstan/data/StrictMockingTestCaseTest.php
new file mode 100644
index 0000000..312bed6
--- /dev/null
+++ b/tests/phpstan/data/StrictMockingTestCaseTest.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\data;
+
+use Lendable\PHPUnitExtensions\TestCase;
+
+final class StrictMockingTestCaseTest extends TestCase {}
diff --git a/tests/phpstan/data/StrictMockingTraitTest.php b/tests/phpstan/data/StrictMockingTraitTest.php
new file mode 100644
index 0000000..c59feb4
--- /dev/null
+++ b/tests/phpstan/data/StrictMockingTraitTest.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\data;
+
+use Lendable\PHPUnitExtensions\StrictMocking;
+use PHPUnit\Framework\TestCase;
+
+class StrictMockingTraitTest extends TestCase
+{
+    use StrictMocking;
+}
diff --git a/tests/phpstan/data/TestCaseTest.php b/tests/phpstan/data/TestCaseTest.php
new file mode 100644
index 0000000..2c9d05d
--- /dev/null
+++ b/tests/phpstan/data/TestCaseTest.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Phpstan\Lendable\PHPUnitExtensions\data;
+
+use PHPUnit\Framework\TestCase;
+
+class TestCaseTest extends TestCase {}