The Problem st crashes whenever an emoji needs to be rendered. It turns out to be an issue with the underlying font rendering library libXft. libXft is the client side font rendering library, using libfreetype, libX11, and the X Render extension to display anti-aliased text. The Solution In its current offical mainline form libXft does not support rendering images. A patch by Maxime Coste exists to add support for BGRA glyphs and scaling, effectively enabling emoji rendering support.