diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index d23e48b..bf97c11 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -15,5 +15,8 @@ jobs:
       - name: Test CGL
         run: ./vendor/bin/phpcs
 
+      - name: Execute PHPStan Code Quality
+        run: ./vendor/bin/phpstan analyse
+
       - name: Execute PHPUnit Tests
         run: ./vendor/bin/phpunit
diff --git a/Classes/Dashboard/Widgets/PageViewsBar.php b/Classes/Dashboard/Widgets/PageViewsBar.php
index 5ee4af4..dd8831c 100644
--- a/Classes/Dashboard/Widgets/PageViewsBar.php
+++ b/Classes/Dashboard/Widgets/PageViewsBar.php
@@ -110,10 +110,15 @@ class PageViewsBar extends AbstractBarChartWidget
         $format = $GLOBALS['TYPO3_CONF_VARS']['SYS']['ddmmyy'] ?: 'Y-m-d';
 
         for ($daysBefore = $days; $daysBefore >= 0; $daysBefore--) {
-            $labels[] = date($format, strtotime('-' . $daysBefore . ' day'));
+            $timeForLabel = strtotime('-' . $daysBefore . ' day');
             $startPeriod = strtotime('-' . $daysBefore . ' day 0:00:00');
             $endPeriod =  strtotime('-' . $daysBefore . ' day 23:59:59');
 
+            if ($timeForLabel === false || $startPeriod === false || $endPeriod === false) {
+                continue;
+            }
+
+            $labels[] = date($format, $timeForLabel);
             $data[] = $this->getPageViewsInPeriod($startPeriod, $endPeriod);
         }
 
diff --git a/Classes/Dashboard/Widgets/SettingsFactory.php b/Classes/Dashboard/Widgets/SettingsFactory.php
index 0892d80..37cb84d 100644
--- a/Classes/Dashboard/Widgets/SettingsFactory.php
+++ b/Classes/Dashboard/Widgets/SettingsFactory.php
@@ -25,6 +25,9 @@ use TYPO3\CMS\Core\Utility\ArrayUtility;
 
 class SettingsFactory
 {
+    /**
+     * @var array
+     */
     private $defaults = [
         'pageViewsBar' => [
             'periodInDays' => 31,
diff --git a/Classes/Domain/Repository/Pageview.php b/Classes/Domain/Repository/Pageview.php
index 069d2ff..97af4cc 100644
--- a/Classes/Domain/Repository/Pageview.php
+++ b/Classes/Domain/Repository/Pageview.php
@@ -36,7 +36,7 @@ class Pageview
         $this->connection = $connection;
     }
 
-    public function add(Model $pageview)
+    public function add(Model $pageview): void
     {
         $this->connection->insert(
             'tx_tracking_pageview',
diff --git a/Tests/Unit/Domain/Model/PageviewTest.php b/Tests/Unit/Domain/Model/PageviewTest.php
index 87f5b1c..c590f23 100644
--- a/Tests/Unit/Domain/Model/PageviewTest.php
+++ b/Tests/Unit/Domain/Model/PageviewTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace DanielSiepmann\Tracking\Unit\Domain\Model;
+namespace DanielSiepmann\Tracking\Tests\Unit\Domain\Model;
 
 /*
  * Copyright (C) 2020 Daniel Siepmann <coding@daniel-siepmann.de>
@@ -33,7 +33,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function canBeCreated()
+    public function canBeCreated(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
 
@@ -52,7 +52,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function returnsPageUid()
+    public function returnsPageUid(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
 
@@ -71,7 +71,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function returnsLanguage()
+    public function returnsLanguage(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
 
@@ -90,7 +90,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function returnsCrdate()
+    public function returnsCrdate(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
         $crdate = new \DateTimeImmutable();
@@ -110,7 +110,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function returnsPageType()
+    public function returnsPageType(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
 
@@ -129,7 +129,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function returnsUrl()
+    public function returnsUrl(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
 
@@ -148,7 +148,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function returnsUserAgent()
+    public function returnsUserAgent(): void
     {
         $language = $this->prophesize(SiteLanguage::class);
 
diff --git a/Tests/Unit/Domain/Pageview/FactoryTest.php b/Tests/Unit/Domain/Pageview/FactoryTest.php
index 0c97d35..521144c 100644
--- a/Tests/Unit/Domain/Pageview/FactoryTest.php
+++ b/Tests/Unit/Domain/Pageview/FactoryTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace DanielSiepmann\Tracking\Unit\Domain\Pageview;
+namespace DanielSiepmann\Tracking\Tests\Unit\Domain\Pageview;
 
 /*
  * Copyright (C) 2020 Daniel Siepmann <coding@daniel-siepmann.de>
@@ -36,7 +36,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnsPageview()
+    public function returnsPageview(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
@@ -57,7 +57,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnedPageviewContainsUserAgent()
+    public function returnedPageviewContainsUserAgent(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
@@ -83,7 +83,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnedPageviewContainsUri()
+    public function returnedPageviewContainsUri(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
@@ -107,7 +107,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnedPageviewContainsPageType()
+    public function returnedPageviewContainsPageType(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
@@ -131,7 +131,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnedPageviewContainsDateTime()
+    public function returnedPageviewContainsDateTime(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
@@ -152,7 +152,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnedPageviewContainsLanguage()
+    public function returnedPageviewContainsLanguage(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
@@ -173,7 +173,7 @@ class FactoryTest extends TestCase
     /**
      * @test
      */
-    public function returnedPageviewContainsPageId()
+    public function returnedPageviewContainsPageId(): void
     {
         $routing = $this->prophesize(PageArguments::class);
         $routing->getPageId()->willReturn(10);
diff --git a/Tests/Unit/Domain/Repository/PageviewTest.php b/Tests/Unit/Domain/Repository/PageviewTest.php
index bd07858..05e6923 100644
--- a/Tests/Unit/Domain/Repository/PageviewTest.php
+++ b/Tests/Unit/Domain/Repository/PageviewTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace DanielSiepmann\Tracking\Unit\Domain\Repository;
+namespace DanielSiepmann\Tracking\Tests\Unit\Domain\Repository;
 
 /*
  * Copyright (C) 2020 Daniel Siepmann <coding@daniel-siepmann.de>
@@ -35,7 +35,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function modelCanBeAdded()
+    public function modelCanBeAdded(): void
     {
         $connection = $this->prophesize(Connection::class);
 
diff --git a/Tests/Unit/Middleware/PageviewTest.php b/Tests/Unit/Middleware/PageviewTest.php
index 5f88677..32fb633 100644
--- a/Tests/Unit/Middleware/PageviewTest.php
+++ b/Tests/Unit/Middleware/PageviewTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace DanielSiepmann\Tracking\Unit\Middleware;
+namespace DanielSiepmann\Tracking\Tests\Unit\Middleware;
 
 /*
  * Copyright (C) 2020 Daniel Siepmann <coding@daniel-siepmann.de>
@@ -41,7 +41,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function doesNotAddBlacklistedRequest()
+    public function doesNotAddBlacklistedRequest(): void
     {
         $repository = $this->prophesize(Repository::class);
         $context = $this->prophesize(Context::class);
@@ -63,7 +63,7 @@ class PageviewTest extends TestCase
     /**
      * @test
      */
-    public function addsPageviewToRepository()
+    public function addsPageviewToRepository(): void
     {
         $repository = $this->prophesize(Repository::class);
         $context = $this->prophesize(Context::class);
diff --git a/composer.json b/composer.json
index cd60acf..1a93f84 100644
--- a/composer.json
+++ b/composer.json
@@ -27,6 +27,7 @@
     },
     "require": {
         "doctrine/dbal": "^2.10",
+        "ext-mbstring": "*",
         "php": "^7.3.0",
         "psr/http-message": "^1.0",
         "psr/http-server-handler": "^1.0",
@@ -56,6 +57,9 @@
     "require-dev": {
         "squizlabs/php_codesniffer": "^3.5",
         "phpunit/phpunit": "^9.0",
-        "typo3/cms-dashboard": "^10.3.0"
+        "typo3/cms-dashboard": "^10.3.0",
+        "phpstan/phpstan": "^0.12.18",
+        "phpstan/extension-installer": "^1.0",
+        "jangregor/phpstan-prophecy": "^0.6.2"
     }
 }
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..51c13e7
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,10 @@
+parameters:
+    level: max
+    paths:
+        - Classes
+        - Tests
+    checkGenericClassInNonGenericObjectType: false
+    checkMissingIterableValueType: false
+    ignoreErrors:
+        - '#Cannot call method fetchAll\(\) on Doctrine\\DBAL\\Driver\\Statement\|int\.#'
+        - '#Cannot call method fetchColumn\(\) on Doctrine\\DBAL\\Driver\\Statement\|int\.#'