diff --git a/composer-require-checker.json b/composer-require-checker.json
index c553a5be..fcb00648 100644
--- a/composer-require-checker.json
+++ b/composer-require-checker.json
@@ -5,6 +5,7 @@
     "array", "string", "int", "float", "bool", "iterable", "callable", "void", "object",
     "Attribute", "Memcached", "Redis", "RedisException",
     "Doctrine\\Common\\Cache\\ArrayCache", "Doctrine\\Common\\Cache\\MemcachedCache", "Doctrine\\Common\\Cache\\RedisCache",
+    "BEAR\\FastlyModule\\FastlyCachePurgerInterface", "BEAR\\FastlyModule\\FastlyPurgeModule",
     "Detection\\MobileDetect"
   ]
 }
diff --git a/composer.json b/composer.json
index 9d8ec013..db6c22f7 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,6 @@
     ],
     "require": {
         "php": "^8.1",
-        "bear/fastly-module": "^1.0",
         "bear/resource": "^1.16.1",
         "bear/sunday": "^1.5",
         "doctrine/annotations": "^1.8 || ^2.0",
@@ -24,6 +23,7 @@
     },
     "require-dev": {
         "ext-redis": "*",
+        "bear/fastly-module": "^1.0",
         "bamarni/composer-bin-plugin": "^1.8",
         "koriym/attributes": "^1.0.1",
         "madapaja/twig-module": "^2.3",
diff --git a/src/Cdn/FastlyModule.php b/src/Cdn/FastlyModule.php
index 65579176..aef8c079 100644
--- a/src/Cdn/FastlyModule.php
+++ b/src/Cdn/FastlyModule.php
@@ -7,8 +7,11 @@
 use BEAR\FastlyModule\FastlyPurgeModule;
 use BEAR\QueryRepository\CdnCacheControlHeaderSetterInterface;
 use BEAR\QueryRepository\PurgerInterface;
+use LogicException;
 use Ray\Di\AbstractModule;
 
+use function class_exists;
+
 final class FastlyModule extends AbstractModule
 {
     public function __construct(
@@ -17,6 +20,10 @@ public function __construct(
         AbstractModule|null $module = null,
     ) {
         parent::__construct($module);
+
+        if (! class_exists(FastlyPurgeModule::class)) {
+            throw new LogicException('Install bear/fastly-module'); // @codeCoverageIgnore
+        }
     }
 
     /**
diff --git a/src/QueryRepository.php b/src/QueryRepository.php
index c948ef81..af713c53 100644
--- a/src/QueryRepository.php
+++ b/src/QueryRepository.php
@@ -64,7 +64,7 @@ public function get(AbstractUri $uri): ResourceState|null
             return null;
         }
 
-        $state->headers[Header::AGE] = (string) (time() - strtotime($state->headers[Header::LAST_MODIFIED]));
+        $state->headers[Header::AGE] = (string) (time() - (int) strtotime($state->headers[Header::LAST_MODIFIED]));
 
         return $state;
     }
@@ -113,6 +113,6 @@ private function getExpiryAtSec(ResourceObject $ro, Cacheable $cacheable): int
         /** @var string $expiryAt */
         $expiryAt = $ro->body[$cacheable->expiryAt];
 
-        return strtotime($expiryAt) - time();
+        return (int) strtotime($expiryAt) - time();
     }
 }