diff --git a/Shoko.Server/API/v3/Controllers/FilterController.cs b/Shoko.Server/API/v3/Controllers/FilterController.cs
index 195224a53..1480bab85 100644
--- a/Shoko.Server/API/v3/Controllers/FilterController.cs
+++ b/Shoko.Server/API/v3/Controllers/FilterController.cs
@@ -344,7 +344,7 @@ [FromQuery] [Range(0, 100)] int pageSize = 50, [FromQuery] [Range(1, int.MaxValu
     /// <param name="includeEmpty">Include <see cref="Series"/> with missing
     ///     <see cref="Episode"/>s in the count.</param>
     /// <returns></returns>
-    [HttpGet("Preview/Group/Letters")]
+    [HttpPost("Preview/Group/Letters")]
     public ActionResult<Dictionary<char, int>> GetPreviewGroupNameLettersInFilter([FromBody] Filter.Input.CreateOrUpdateFilterBody filter, [FromQuery] bool includeEmpty = false)
     {
         // Directories should only contain sub-filters, not groups and series.