How to insert one row spacing between tiles in a tiled image using Imagemagick?

Question

I have a bunch of images that I want to tile together in one row. This can be done using Imagemagick montage like this

montage `ls tile*.png` -tile x1 -gravity west -geometry 1x1\<+0+0 out_file.png

However, now I want to insert one pixel of spacing after each tile. I played with -tile-offset -1+0 for a bit but this would not change anything. Similarly, I could use -geometry 1x1\<+1+0, but this would introduce two pixels of spacing instead of one.

How can I do one pixel of spacing between tiles?