diff --git a/src/attachments/models.py b/src/attachments/models.py
index f8be2bd..7021199 100644
--- a/src/attachments/models.py
+++ b/src/attachments/models.py
@@ -86,7 +86,7 @@ class Attachment(models.Model):
             "resize_height": settings.SHORTPIXEL_RESIZE_HEIGHT,
             "keep_exif": 1,
             "file_paths": json.dumps(
-                [f"{self.original_file.name}:{self.original_file.path}"],
+                {self.original_file.name: self.original_file.path},
             ),
         }
         data = {**base_data, **post_data}