Hi Hans, there are two bugs with the \useMPenvironmentbuffer command. 1. The TeX command uses the wrong name to pass the name to Lua: \unexpanded\def\useMPenvironmentbuffer[#1]% - {\clf_mpsetfrombuffer{#1}} + {\clf_mptexsetfrombuffer{#1}} 2. The Lua function in mlib-ctx.lua uses a non existing function to load the buffer content: function mptex.setfrombuffer(name) - environments[#environments+1] = buffers.content(name) + environments[#environments+1] = buffers.getcontent(name) end Wolfgang