diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8e8aee24..c86d1ef1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## Next Release
+
+- Sends card details in the request body instead of the URL query string when `referralCustomer->addCreditCard` creates a Stripe token
+
 ## v8.8.3 (2026-08-26)
 
 - Preserves caller-provided plain PHP objects in request params so `(object) []` is sent as an empty JSON object (`{}`) instead of being stringified
diff --git a/lib/EasyPost/Service/ReferralCustomerService.php b/lib/EasyPost/Service/ReferralCustomerService.php
index 9ff66f32..a65d8a46 100644
--- a/lib/EasyPost/Service/ReferralCustomerService.php
+++ b/lib/EasyPost/Service/ReferralCustomerService.php
@@ -220,7 +220,9 @@ private function createStripeToken(
 
         $guzzleClient = new Client();
 
-        $requestOptions['query'] = $creditCardDetails;
+        // Card details must travel in the form-encoded request body, never in the URL,
+        // so they cannot end up in access logs, proxy logs, or Referer headers.
+        $requestOptions['form_params'] = $creditCardDetails;
         $requestOptions['headers'] = $headers;
         $requestOptions['http_errors'] = false;