diff --git a/composer.json b/composer.json
index 798934f..7eecaa0 100644
--- a/composer.json
+++ b/composer.json
@@ -15,6 +15,7 @@
     },
     "require": {
         "symfony/http-client": "^6.4 || ^7.0",
-        "amphp/http-client": "^4.2.1"
+        "amphp/http-client": "^4.2.1",
+        "knplabs/php-json-schema": "^0.1.0"
     }
 }
diff --git a/src/MistralClient.php b/src/MistralClient.php
index dc6322c..975c1c1 100644
--- a/src/MistralClient.php
+++ b/src/MistralClient.php
@@ -5,6 +5,7 @@
 ini_set('default_socket_timeout', '-1');
 
 use Generator;
+use KnpLabs\JsonSchema\ObjectSchema;
 use Symfony\Component\HttpClient\HttpClient;
 use Symfony\Component\HttpClient\Retry\GenericRetryStrategy;
 use Symfony\Component\HttpClient\RetryableHttpClient;
@@ -207,6 +208,9 @@ protected function makeChatCompletionRequest(Messages $messages, array $params,
         }
 
         if (isset($params['guided_json']) && is_object($params['guided_json'])) {
+            if ($params['guided_json'] instanceof ObjectSchema) {
+                $params['guided_json'] = $params['guided_json']->jsonSerialize();
+            }
             $return['guided_json'] = json_encode($params['guided_json']);
         }