@Christian-Ehrlicher Oh! I'm sorry. My first search on bugreports.qt.io only found closed topics that did not fix the problem, and I was too shy to open a new one while so many others were closed. Then I found this open topic on this forum. Anyway, after a second search on bugreports.qt.io, I found this: https://bugreports.qt.io/browse/QTIFW-2375 This will probably fix the problem. I guess, we'll have to wait for v4.3.0... In the meantime, I can use my old 4-core computer to build installers; or use zip compression instead of 7zip, which results in a 10% larger file size (+50MB in my case).