diff --git a/bypy/sources.json b/bypy/sources.json
index 65e3e5d370..e464847f1a 100644
--- a/bypy/sources.json
+++ b/bypy/sources.json
@@ -80,6 +80,7 @@
 
     {
         "name": "xz",
+        "os": "macos,linux",
         "unix": {
             "filename": "xz-5.2.4.tar.gz",
             "hash": "md5:5ace3264bdd00c65eeec2891346f65e6",
diff --git a/bypy/windows.conf b/bypy/windows.conf
index b163e3732b..6385ad049b 100644
--- a/bypy/windows.conf
+++ b/bypy/windows.conf
@@ -2,6 +2,7 @@
 # git.exe must be in PATH. Must have ~120GB available disk space and 8GB RAM
 # Install certifi in python 3 with:
 # py.exe -m pip install certifi
+# Install python2 which is needed to build Qt WebEngine
 # Copy opengl32sw.dll from
 # https://download.qt.io/development_releases/prebuilt/llvmpipe/windows/
 # to C:/mesa/32 and C:/mesa/64
@@ -11,6 +12,7 @@
 vm_name 'windows-calibre-build'
 root 'C:/r'
 python 'py.exe'
+python2 'C:/Python27/python.exe'
 perl 'C:/Strawberry/perl/bin/perl.exe'
 ruby 'C:/Ruby27-x64/bin/ruby.exe'
 mesa 'C:/mesa'