diff --git a/backend/API/Controllers/FilamentsController.cs b/backend/API/Controllers/FilamentsController.cs
index 5bb951e..f39c81d 100644
--- a/backend/API/Controllers/FilamentsController.cs
+++ b/backend/API/Controllers/FilamentsController.cs
@@ -40,6 +40,7 @@ public class FilamentsController : ControllerBase
     /// <response code="200">Returns the paginated list of filament spools.</response>
     [HttpGet]
     [ProducesResponseType(typeof(PagedResponse<FilamentResponse>), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
     public async Task<ActionResult<PagedResponse<FilamentResponse>>> GetFilaments(
         [FromQuery] FilamentQueryParameters query)
     {