diff --git a/composer.json b/composer.json
index 4d12bce7..d84721e3 100644
--- a/composer.json
+++ b/composer.json
@@ -28,6 +28,7 @@
         "php-mock/php-mock-phpunit": "^2.0",
         "phpstan/phpstan-phpunit": "0.9.2",
         "phpstan/phpstan-shim": "0.9.1",
+        "phpstan/phpstan-strict-rules": "^0.9.0",
         "phpunit/phpunit": "^6.4",
         "squizlabs/php_codesniffer": "^3.0"
     },
diff --git a/phpstan.neon b/phpstan.neon
index 52d9fbe2..fd132839 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,3 +1,5 @@
+includes:
+    - ./vendor/phpstan/phpstan-strict-rules/rules.neon
 parameters:
     ignoreErrors:
         - '#Function uuid_create not found#'
diff --git a/src/Provider/Node/FallbackNodeProvider.php b/src/Provider/Node/FallbackNodeProvider.php
index 730e6471..cc3a4489 100644
--- a/src/Provider/Node/FallbackNodeProvider.php
+++ b/src/Provider/Node/FallbackNodeProvider.php
@@ -47,7 +47,7 @@ public function __construct(array $providers)
     public function getNode()
     {
         foreach ($this->nodeProviders as $provider) {
-            if ($node = $provider->getNode()) {
+            if ((bool) ($node = $provider->getNode())) {
                 return $node;
             }
         }
diff --git a/src/Uuid.php b/src/Uuid.php
index ccf1e626..d229b58e 100644
--- a/src/Uuid.php
+++ b/src/Uuid.php
@@ -597,7 +597,7 @@ public function toString()
      */
     public static function getFactory()
     {
-        if (!self::$factory) {
+        if (!(self::$factory instanceof UuidFactoryInterface)) {
             self::$factory = new UuidFactory();
         }