diff --git a/src/Responses/FineTuning/ListJobsResponse.php b/src/Responses/FineTuning/ListJobsResponse.php
index e7396d0f..9b402412 100644
--- a/src/Responses/FineTuning/ListJobsResponse.php
+++ b/src/Responses/FineTuning/ListJobsResponse.php
@@ -12,12 +12,12 @@
 use OpenAI\Testing\Responses\Concerns\Fakeable;
 
 /**
- * @implements ResponseContract<array{object: string, data: array<int, array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>, has_more: bool}>
+ * @implements ResponseContract<array{object: string, data: array<int, array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters?: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>, has_more: bool}>
  */
 final class ListJobsResponse implements ResponseContract, ResponseHasMetaInformationContract
 {
     /**
-     * @use ArrayAccessible<array{object: string, data: array<int, array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>, has_more: bool}>
+     * @use ArrayAccessible<array{object: string, data: array<int, array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters?: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>, has_more: bool}>
      */
     use ArrayAccessible;
 
@@ -37,7 +37,7 @@ private function __construct(
     /**
      * Acts as static factory, and returns a new Response instance.
      *
-     * @param  array{object: string, data: array<int, array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>, has_more: bool}  $attributes
+     * @param  array{object: string, data: array<int, array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters?: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>, has_more: bool}  $attributes
      */
     public static function from(array $attributes, MetaInformation $meta): self
     {
diff --git a/src/Responses/FineTuning/RetrieveJobResponse.php b/src/Responses/FineTuning/RetrieveJobResponse.php
index 641148c3..6d6974f3 100644
--- a/src/Responses/FineTuning/RetrieveJobResponse.php
+++ b/src/Responses/FineTuning/RetrieveJobResponse.php
@@ -12,12 +12,12 @@
 use OpenAI\Testing\Responses\Concerns\Fakeable;
 
 /**
- * @implements ResponseContract<array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>
+ * @implements ResponseContract<array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters?: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>
  */
 final class RetrieveJobResponse implements ResponseContract, ResponseHasMetaInformationContract
 {
     /**
-     * @use ArrayAccessible<array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>
+     * @use ArrayAccessible<array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters?: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code: string, param: ?string, message: string}}>
      */
     use ArrayAccessible;
 
@@ -34,7 +34,7 @@ private function __construct(
         public readonly int $createdAt,
         public readonly ?int $finishedAt,
         public readonly ?string $fineTunedModel,
-        public readonly RetrieveJobResponseHyperparameters $hyperparameters,
+        public readonly ?RetrieveJobResponseHyperparameters $hyperparameters,
         public readonly string $organizationId,
         public readonly array $resultFiles,
         public readonly string $status,
@@ -48,7 +48,7 @@ private function __construct(
     /**
      * Acts as static factory, and returns a new Response instance.
      *
-     * @param  array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code?: string, param?: ?string, message?: string}}  $attributes
+     * @param  array{id: string, object: string, model: string, created_at: int, finished_at: ?int, fine_tuned_model: ?string, hyperparameters?: array{n_epochs: int|string, batch_size: int|string|null, learning_rate_multiplier: float|string|null}, organization_id: string, result_files: array<int, string>, status: string, validation_file: ?string, training_file: string, trained_tokens: ?int, error: ?array{code?: string, param?: ?string, message?: string}}  $attributes
      */
     public static function from(array $attributes, MetaInformation $meta): self
     {
@@ -59,7 +59,9 @@ public static function from(array $attributes, MetaInformation $meta): self
             $attributes['created_at'],
             $attributes['finished_at'],
             $attributes['fine_tuned_model'],
-            RetrieveJobResponseHyperparameters::from($attributes['hyperparameters']),
+            isset($attributes['hyperparameters'])
+                ? RetrieveJobResponseHyperparameters::from($attributes['hyperparameters'])
+                : null,
             $attributes['organization_id'],
             $attributes['result_files'],
             $attributes['status'],
@@ -81,14 +83,13 @@ public static function from(array $attributes, MetaInformation $meta): self
      */
     public function toArray(): array
     {
-        return [
+        $result = [
             'id' => $this->id,
             'object' => $this->object,
             'model' => $this->model,
             'created_at' => $this->createdAt,
             'finished_at' => $this->finishedAt,
             'fine_tuned_model' => $this->fineTunedModel,
-            'hyperparameters' => $this->hyperparameters->toArray(),
             'organization_id' => $this->organizationId,
             'result_files' => $this->resultFiles,
             'status' => $this->status,
@@ -97,5 +98,11 @@ public function toArray(): array
             'trained_tokens' => $this->trainedTokens,
             'error' => $this->error?->toArray(),
         ];
+
+        if ($this->hyperparameters) {
+            $result['hyperparameters'] = $this->hyperparameters->toArray();
+        }
+
+        return $result;
     }
 }
diff --git a/tests/Fixtures/FineTuning.php b/tests/Fixtures/FineTuning.php
index 735c5f57..825e988c 100644
--- a/tests/Fixtures/FineTuning.php
+++ b/tests/Fixtures/FineTuning.php
@@ -12,11 +12,6 @@ function fineTuningJobCreateResource(): array
         'created_at' => 1614807352,
         'finished_at' => null,
         'fine_tuned_model' => null,
-        'hyperparameters' => [
-            'n_epochs' => 9,
-            'batch_size' => 'auto',
-            'learning_rate_multiplier' => 'auto',
-        ],
         'organization_id' => 'org-jwe45798ASN82s',
         'result_files' => [],
         'status' => 'created',
@@ -24,6 +19,11 @@ function fineTuningJobCreateResource(): array
         'training_file' => 'file-abc123',
         'trained_tokens' => null,
         'error' => null,
+        'hyperparameters' => [
+            'n_epochs' => 9,
+            'batch_size' => 'auto',
+            'learning_rate_multiplier' => 'auto',
+        ],
     ];
 }
 
@@ -39,11 +39,6 @@ function fineTuningJobRetrieveResource(): array
         'created_at' => 1614807352,
         'finished_at' => 1692819450,
         'fine_tuned_model' => 'ft:gpt-3.5-turbo-0613:jwe-dev::7qnxQ0sQ',
-        'hyperparameters' => [
-            'n_epochs' => 9,
-            'batch_size' => 1,
-            'learning_rate_multiplier' => 2.2,
-        ],
         'organization_id' => 'org-jwe45798ASN82s',
         'result_files' => [
             'file-1bl05WrhsKDDEdg8XSP617QF',
@@ -53,6 +48,11 @@ function fineTuningJobRetrieveResource(): array
         'training_file' => 'file-abc123',
         'trained_tokens' => 5049,
         'error' => null,
+        'hyperparameters' => [
+            'n_epochs' => 9,
+            'batch_size' => 1,
+            'learning_rate_multiplier' => 2.2,
+        ],
     ];
 }
 
@@ -68,11 +68,6 @@ function fineTuningFailedJobRetrieveResource(): array
         'created_at' => 1614807352,
         'finished_at' => null,
         'fine_tuned_model' => null,
-        'hyperparameters' => [
-            'n_epochs' => 9,
-            'batch_size' => 'auto',
-            'learning_rate_multiplier' => 'auto',
-        ],
         'organization_id' => 'org-jwe45798ASN82s',
         'result_files' => [],
         'status' => 'failed',
@@ -84,6 +79,11 @@ function fineTuningFailedJobRetrieveResource(): array
             'param' => 'training_file',
             'message' => 'Training file has 3 example(s), but must have at least 10 examples',
         ],
+        'hyperparameters' => [
+            'n_epochs' => 9,
+            'batch_size' => 'auto',
+            'learning_rate_multiplier' => 'auto',
+        ],
     ];
 }
 
diff --git a/tests/Responses/FineTuning/RetrieveJobResponse.php b/tests/Responses/FineTuning/RetrieveJobResponse.php
index c85b5115..a458acd5 100644
--- a/tests/Responses/FineTuning/RetrieveJobResponse.php
+++ b/tests/Responses/FineTuning/RetrieveJobResponse.php
@@ -47,6 +47,26 @@
         ->meta()->toBeInstanceOf(MetaInformation::class);
 });
 
+test('from retrieve response with missing hyperparameters', function () {
+    $payload = fineTuningJobRetrieveResource();
+    unset($payload['hyperparameters']);
+    $result = RetrieveJobResponse::from($payload, meta());
+
+    expect($result)
+        ->toBeInstanceOf(RetrieveJobResponse::class)
+        ->hyperparameters->toBeNull();
+});
+
+test('from retrieve response with null hyperparameters', function () {
+    $payload = fineTuningJobRetrieveResource();
+    $payload['hyperparameters'] = null;
+    $result = RetrieveJobResponse::from($payload, meta());
+
+    expect($result)
+        ->toBeInstanceOf(RetrieveJobResponse::class)
+        ->hyperparameters->toBeNull();
+});
+
 test('as array accessible', function () {
     $result = RetrieveJobResponse::from(fineTuningJobCreateResource(), meta());