diff --git a/lib/filestack/config.rb b/lib/filestack/config.rb
index 9ce05c5..10980e4 100644
--- a/lib/filestack/config.rb
+++ b/lib/filestack/config.rb
@@ -53,6 +53,6 @@ class TransformConfig
     redeye ascii filetype_conversion quality urlscreenshot
     no_metadata fallback pdfinfo pdfconvert cache auto_image
     minify_js minify_css animate video_convert video_playlist
-    compress content
+    compress content imagesize
   ].freeze
 end