diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index ee7ecabd..777f8d3d 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -113,5 +113,8 @@ Please also check the code structure using PHPMD:
 
     vendor/bin/phpmd Classes/ text Configuration/PHPMD/rules.xml
 
+And also please run the static code analysis:
+
+    vendor/bin/phpstan analyse -l 5 Classes/ Tests/
 
 Please make your code clean, well-readable and easy to understand.
diff --git a/.travis.yml b/.travis.yml
index 27d587a8..fe09d0ec 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -57,6 +57,11 @@ script:
     echo "Running the integration tests";
     vendor/bin/phpunit Tests/Integration/;
 
+  - >
+    echo;
+    echo "Running the static analysis";
+    vendor/bin/phpstan analyse -l 5 Classes/ Tests/;
+
   - >
     echo;
     echo "Running PHPMD";
diff --git a/Classes/Core/Bootstrap.php b/Classes/Core/Bootstrap.php
index 8e20816c..7b962060 100644
--- a/Classes/Core/Bootstrap.php
+++ b/Classes/Core/Bootstrap.php
@@ -20,7 +20,7 @@
 class Bootstrap
 {
     /**
-     * @var Bootstrap
+     * @var Bootstrap|null
      */
     private static $instance = null;
 
diff --git a/Tests/Integration/Domain/Repository/Identity/AdministratorTokenRepositoryTest.php b/Tests/Integration/Domain/Repository/Identity/AdministratorTokenRepositoryTest.php
index c3e05691..f91578b6 100644
--- a/Tests/Integration/Domain/Repository/Identity/AdministratorTokenRepositoryTest.php
+++ b/Tests/Integration/Domain/Repository/Identity/AdministratorTokenRepositoryTest.php
@@ -3,6 +3,7 @@
 
 namespace PhpList\PhpList4\Tests\Integration\Domain\Repository\Identity;
 
+use Doctrine\Common\Persistence\ObjectRepository;
 use PhpList\PhpList4\Core\Bootstrap;
 use PhpList\PhpList4\Domain\Model\Identity\AdministratorToken;
 use PhpList\PhpList4\Domain\Repository\Identity\AdministratorTokenRepository;
@@ -41,7 +42,7 @@ class AdministratorTokenRepositoryTest extends TestCase
     private $dataSet = null;
 
     /**
-     * @var AdministratorTokenRepository
+     * @var AdministratorTokenRepository|ObjectRepository
      */
     private $subject = null;
 
diff --git a/composer.json b/composer.json
index 70b2607d..ff88f49c 100644
--- a/composer.json
+++ b/composer.json
@@ -40,6 +40,7 @@
         "phpunit/phpunit": "^6.2.2",
         "phpunit/dbunit": "^3.0.0",
         "squizlabs/php_codesniffer": "^3.0.1",
+        "phpstan/phpstan": "^0.7.0",
         "phpmd/phpmd": "^2.6.0"
     },
     "suggest": {
@@ -57,6 +58,11 @@
             "core/helper/Shortcuts.php"
         ]
     },
+    "autoload-dev": {
+        "psr-4": {
+            "PhpList\\PhpList4\\Tests\\": "Tests/"
+        }
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "4.0.0-dev"