diff --git a/speckles.py b/speckles.py
index 45f6f3e..745bf42 100644
--- a/speckles.py
+++ b/speckles.py
@@ -298,7 +298,7 @@ def make_wallpaper(
             buf.seek(0)
         else:
             with pyvips.Image.svgload_buffer(content.as_str().encode("utf-8")) as image:
-                buf = image.write_to_buffer(fileformat)
+                buf = image.write_to_buffer("." + fileformat)
         return StreamingResponse(content=buf, media_type=MEDIA_TYPES[fileformat])