diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 6429212..ecf21a2 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: PHP Composer
         uses: php-actions/composer@v6
       - name: Tests
diff --git a/lib/Shift4/Shift4Gateway.php b/lib/Shift4/Shift4Gateway.php
index 9acf651..f6dfb70 100644
--- a/lib/Shift4/Shift4Gateway.php
+++ b/lib/Shift4/Shift4Gateway.php
@@ -10,7 +10,7 @@
 
 class Shift4Gateway
 {
-    const VERSION = '3.3.0';
+    const VERSION = '4.0.0';
     const DEFAULT_ENDPOINT = 'https://api.shift4.com';
     const DEFAULT_UPLOADS_ENDPOINT = "https://uploads.api.shift4.com/";
 
@@ -227,17 +227,16 @@ public function listPaymentMethods($request)
      */
     public function createSubscription($request, RequestOptions $requestOptions = null)
     {
-        return $this->post('/customers/{customerId}/subscriptions', $request, '\Shift4\Response\Subscription', $requestOptions);
+        return $this->post('/subscriptions', $request, '\Shift4\Response\Subscription', $requestOptions);
     }
 
     /**
-     * @param string $customerId
      * @param string $subscriptionId
      * @return \Shift4\Response\Subscription
      */
-    public function retrieveSubscription($customerId, $subscriptionId)
+    public function retrieveSubscription($subscriptionId)
     {
-        return $this->get("/customers/{$customerId}/subscriptions/{$subscriptionId}", '\Shift4\Response\Subscription');
+        return $this->get("/subscriptions/{$subscriptionId}", '\Shift4\Response\Subscription');
     }
 
     /**
@@ -246,7 +245,7 @@ public function retrieveSubscription($customerId, $subscriptionId)
      */
     public function updateSubscription($request, RequestOptions $requestOptions = null)
     {
-        return $this->post('/customers/{customerId}/subscriptions/{subscriptionId}', $request, '\Shift4\Response\Subscription', $requestOptions);
+        return $this->post('/subscriptions/{subscriptionId}', $request, '\Shift4\Response\Subscription', $requestOptions);
     }
 
     /**
@@ -255,7 +254,7 @@ public function updateSubscription($request, RequestOptions $requestOptions = nu
      */
     public function cancelSubscription($request)
     {
-        return $this->delete('/customers/{customerId}/subscriptions/{subscriptionId}', $request, '\Shift4\Response\Subscription');
+        return $this->delete('/subscriptions/{subscriptionId}', $request, '\Shift4\Response\Subscription');
     }
 
     /**
@@ -264,7 +263,7 @@ public function cancelSubscription($request)
      */
     public function listSubscriptions($request)
     {
-        return $this->getList('/customers/{customerId}/subscriptions', $request, '\Shift4\Response\Subscription');
+        return $this->getList('/subscriptions', $request, '\Shift4\Response\Subscription');
     }
 
     /**
diff --git a/tests/SubscriptionTest.php b/tests/SubscriptionTest.php
index a202a8a..9f2c540 100644
--- a/tests/SubscriptionTest.php
+++ b/tests/SubscriptionTest.php
@@ -34,7 +34,7 @@ function testRetrieveSubscription()
         $subscription = $this->gateway->createSubscription($request);
         
         // when
-        $subscription = $this->gateway->retrieveSubscription($subscription->getCustomerId(), $subscription->getId());
+        $subscription = $this->gateway->retrieveSubscription($subscription->getId());
         
         // then
         Assert::assertSubscription($request, $subscription);
diff --git a/tests/utils/Assert.php b/tests/utils/Assert.php
index 92723ec..21c2b28 100644
--- a/tests/utils/Assert.php
+++ b/tests/utils/Assert.php
@@ -228,7 +228,7 @@ public static function assertValidCheckoutRequest($signedCheckoutRequest)
         $error = substr($error, 0, strpos($error, "\">") + 1);
         self::assertFalse($hasError, "Error for checkout url $checkoutUrl: $error");
         
-        $hasInput = (strpos($checkoutPage, '<input') !== false);
+        $hasInput = (strpos($checkoutPage, 'Shift4Checkout.open(') !== false);
         self::assertTrue($hasInput);
     }