diff --git a/README.md b/README.md
index 965c25a..131023f 100644
--- a/README.md
+++ b/README.md
@@ -55,7 +55,8 @@ return MonitorConfig::configure()
     ->minPackageVersion('rector/rector', '2.2')
 
     // other rules
-    ->noPhpstanBaseline();
+    ->noPhpstanBaseline()
+    ->minPHPStanLevel(8);
 ```
 
 <br>
diff --git a/composer.json b/composer.json
index 4e3d743..d0d1be8 100644
--- a/composer.json
+++ b/composer.json
@@ -25,9 +25,9 @@
         "shipmonk/composer-dependency-analyser": "^1.8",
         "symplify/phpstan-extensions": "^12.0",
         "symplify/phpstan-rules": "^14.10",
-        "tomasvotruba/class-leak": "^2.1",
         "tomasvotruba/unused-public": "^2.2",
-        "tracy/tracy": "^2.12"
+        "tracy/tracy": "^2.12",
+        "tomasvotruba/class-leak": "^2.1.3"
     },
     "autoload": {
         "psr-4": {
diff --git a/monitor.php b/monitor.php
index c034bac..ec3f36e 100644
--- a/monitor.php
+++ b/monitor.php
@@ -30,4 +30,5 @@
     ->minPackageVersion('rector/rector', '2.0')
 
     // other rules
-    ->noPhpstanBaseline();
+    ->noPhpstanBaseline()
+    ->minPHPStanLevel(8);
diff --git a/src/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor.php b/src/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor.php
new file mode 100644
index 0000000..43ccc6f
--- /dev/null
+++ b/src/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Monitor\Analyze\RuleProcessor\MetafileProcessor;
+
+use Nette\Neon\Neon;
+use Rector\Monitor\Analyze\Contract\RuleProcessorInterface;
+use Rector\Monitor\Analyze\Reporting\ErrorCollector;
+use Rector\Monitor\Config\MonitorConfig;
+use Rector\Monitor\ValueObject\ComposerJson;
+
+/**
+ * @see \Rector\Monitor\Tests\Analyze\RuleProcessor\MetafileProcessor\TooLowPHPStanLevelMetafileProcessor\TooLowPHPStanLevelMetafileProcessorTest
+ */
+final readonly class TooLowPHPStanLevelMetafileProcessor implements RuleProcessorInterface
+{
+    public function process(
+        MonitorConfig $monitorConfig,
+        ComposerJson $composerJson,
+        ErrorCollector $errorCollector
+    ): void {
+        $minPHPStanLevel = $monitorConfig->getMinPHPStanLevel();
+        if ($minPHPStanLevel === null) {
+            return;
+        }
+
+        foreach ($monitorConfig->getRepositoryCollection()->all() as $repository) {
+            foreach ($repository->getRootFiles() as $repositoryRootFile) {
+                if (! str_contains($repositoryRootFile->getFilename(), 'phpstan')) {
+                    continue;
+                }
+
+                if (! str_ends_with($repositoryRootFile->getFilename(), '.neon')) {
+                    continue;
+                }
+
+                if (str_contains($repositoryRootFile->getFilename(), 'baseline')) {
+                    continue;
+                }
+
+                $phpstanLevel = $this->resolvePHPStanLevel($repositoryRootFile->getContents());
+                if ($phpstanLevel === null) {
+                    continue;
+                }
+
+                if ($phpstanLevel >= $minPHPStanLevel) {
+                    continue;
+                }
+
+                $errorCollector->addErrorMessage(sprintf(
+                    ' * PHPStan level in "<fg=green>%s</>" is <fg=red>too low</>. Current level "<fg=yellow>%d</>", should be at least "<fg=yellow>%d</>"',
+                    $repositoryRootFile->getFilename(),
+                    $phpstanLevel,
+                    $minPHPStanLevel
+                ));
+            }
+        }
+    }
+
+    private function resolvePHPStanLevel(string $neonContents): ?int
+    {
+        $decoded = Neon::decode($neonContents);
+        if (! is_array($decoded)) {
+            return null;
+        }
+
+        $level = $decoded['parameters']['level'] ?? null;
+        if ($level === null) {
+            return null;
+        }
+
+        if ($level === 'max') {
+            return 10;
+        }
+
+        if (is_int($level)) {
+            return $level;
+        }
+
+        if (is_string($level) && preg_match('#^\d+$#', $level) === 1) {
+            return (int) $level;
+        }
+
+        return null;
+    }
+}
diff --git a/src/Config/MonitorConfig.php b/src/Config/MonitorConfig.php
index 63ff6d6..866d8f5 100644
--- a/src/Config/MonitorConfig.php
+++ b/src/Config/MonitorConfig.php
@@ -38,6 +38,8 @@ final class MonitorConfig
 
     private bool $noPHPStanBaseline = false;
 
+    private ?int $minPHPStanLevel = null;
+
     private ?RepositoryCollection $repositoryCollection = null;
 
     public static function configure(): self
@@ -153,6 +155,20 @@ public function isNoPHPStanBaseline(): bool
         return $this->noPHPStanBaseline;
     }
 
+    public function minPHPStanLevel(int $minPHPStanLevel): self
+    {
+        Assert::range($minPHPStanLevel, 0, 10);
+
+        $this->minPHPStanLevel = $minPHPStanLevel;
+
+        return $this;
+    }
+
+    public function getMinPHPStanLevel(): ?int
+    {
+        return $this->minPHPStanLevel;
+    }
+
     /**
      * @return string[]
      */
diff --git a/src/Helper/SymfonyColumnStyler.php b/src/Helper/SymfonyColumnStyler.php
index 3c3f18f..4e05a74 100644
--- a/src/Helper/SymfonyColumnStyler.php
+++ b/src/Helper/SymfonyColumnStyler.php
@@ -43,8 +43,6 @@ public static function styleHighsAndLows(array $tableRow): array
                 $secondVersion
             )
         );
-
-        $uniqueValues = array_unique($stringValues);
         $highValue = array_shift($stringValues);
         $lowValue = array_pop($stringValues);
 
diff --git a/templates/monitor.php.dist b/templates/monitor.php.dist
index 73dc9b9..25c5128 100644
--- a/templates/monitor.php.dist
+++ b/templates/monitor.php.dist
@@ -24,4 +24,5 @@ return MonitorConfig::configure()
 
     // other rules
     // ->noPhpstanBaseline()
+    // ->minPHPStanLevel(8)
     ;
diff --git a/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/Fixture/phpstan-high.neon b/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/Fixture/phpstan-high.neon
new file mode 100644
index 0000000..22254bc
--- /dev/null
+++ b/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/Fixture/phpstan-high.neon
@@ -0,0 +1,2 @@
+parameters:
+    level: max
diff --git a/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/Fixture/phpstan-too-low.neon b/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/Fixture/phpstan-too-low.neon
new file mode 100644
index 0000000..4e10079
--- /dev/null
+++ b/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/Fixture/phpstan-too-low.neon
@@ -0,0 +1,2 @@
+parameters:
+    level: 3
diff --git a/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/TooLowPHPStanLevelMetafileProcessorTest.php b/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/TooLowPHPStanLevelMetafileProcessorTest.php
new file mode 100644
index 0000000..06b2462
--- /dev/null
+++ b/tests/Analyze/RuleProcessor/MetafileProcessor/TooLowPHPStanLevelMetafileProcessor/TooLowPHPStanLevelMetafileProcessorTest.php
@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Monitor\Tests\Analyze\RuleProcessor\MetafileProcessor\TooLowPHPStanLevelMetafileProcessor;
+
+use Override;
+use Rector\Monitor\Analyze\Reporting\ErrorCollector;
+use Rector\Monitor\Analyze\RuleProcessor\MetafileProcessor\TooLowPHPStanLevelMetafileProcessor;
+use Rector\Monitor\Config\MonitorConfig;
+use Rector\Monitor\Tests\AbstractTestCase;
+use Rector\Monitor\ValueObject\ComposerJson;
+use Symfony\Component\Finder\SplFileInfo;
+
+final class TooLowPHPStanLevelMetafileProcessorTest extends AbstractTestCase
+{
+    private TooLowPHPStanLevelMetafileProcessor $tooLowPHPStanLevelMetafileProcessor;
+
+    #[Override]
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->tooLowPHPStanLevelMetafileProcessor = $this->make(TooLowPHPStanLevelMetafileProcessor::class);
+    }
+
+    public function testReportsTooLowLevel(): void
+    {
+        $monitorConfig = $this->createMonitorConfigWithRepository(__DIR__ . '/Fixture/phpstan-too-low.neon');
+        $monitorConfig->minPHPStanLevel(8);
+
+        $errorCollector = new ErrorCollector();
+        $this->tooLowPHPStanLevelMetafileProcessor->process(
+            $monitorConfig,
+            new ComposerJson('https://example.com/some/repo.git', []),
+            $errorCollector
+        );
+
+        $errorMessages = $errorCollector->getErrorMessages();
+        $this->assertCount(1, $errorMessages);
+        $this->assertStringContainsString('too low', $errorMessages[0]);
+    }
+
+    public function testSkipsWhenLevelIsHighEnough(): void
+    {
+        $monitorConfig = $this->createMonitorConfigWithRepository(__DIR__ . '/Fixture/phpstan-high.neon');
+        $monitorConfig->minPHPStanLevel(8);
+
+        $errorCollector = new ErrorCollector();
+        $this->tooLowPHPStanLevelMetafileProcessor->process(
+            $monitorConfig,
+            new ComposerJson('https://example.com/some/repo.git', []),
+            $errorCollector
+        );
+
+        $this->assertEmpty($errorCollector->getErrorMessages());
+    }
+
+    public function testSkipsWhenNoMinLevelConfigured(): void
+    {
+        $monitorConfig = $this->createMonitorConfigWithRepository(__DIR__ . '/Fixture/phpstan-too-low.neon');
+
+        $errorCollector = new ErrorCollector();
+        $this->tooLowPHPStanLevelMetafileProcessor->process(
+            $monitorConfig,
+            new ComposerJson('https://example.com/some/repo.git', []),
+            $errorCollector
+        );
+
+        $this->assertEmpty($errorCollector->getErrorMessages());
+    }
+
+    private function createMonitorConfigWithRepository(string $phpstanNeonPath): MonitorConfig
+    {
+        $monitorConfig = new MonitorConfig();
+        $monitorConfig->addRepositories(['https://example.com/some/repo.git']);
+
+        $repository = $monitorConfig->getRepositoryCollection()
+            ->all()[0];
+        $repository->decorateRootFiles([new SplFileInfo($phpstanNeonPath, '', basename($phpstanNeonPath))]);
+
+        return $monitorConfig;
+    }
+}