Image Sizer Duplicate File Path

I’m using Image Sizer and I changed the base cache to a custom one to keep my files organized. My problem is that while my tag looks like this:

{exp:imgsizer:size src="{image}" width="100" height="100" quality="50" base_cache="/home/mysite/root/assets/images/gallery/thumbs/"}

The outputted file path looks like this:

/assets/images/gallery/thumbs/assets/images/gallery/car-100x100.jpg

The image source is duplicated, so it created 3 new directories inside the directory I pointed it to. What did I do wrong?