diff --git a/src/resources/responses/responses.ts b/src/resources/responses/responses.ts
index adf2aafb1..813b9b408 100644
--- a/src/resources/responses/responses.ts
+++ b/src/resources/responses/responses.ts
@@ -2033,7 +2033,7 @@ export interface ResponseInputImage {
    * The detail level of the image to be sent to the model. One of `high`, `low`, or
    * `auto`. Defaults to `auto`.
    */
-  detail: 'low' | 'high' | 'auto';
+  detail?: 'low' | 'high' | 'auto';
 
   /**
    * The type of the input item. Always `input_image`.