diff --git a/.appveyor.yml b/.appveyor.yml
index d5ba2b48..e63d0930 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -39,10 +39,10 @@ install:
   - set PATH=c:\msys64\%MSYSTEM%\bin;c:\msys64\usr\bin;%PATH%
   - if defined MSVC call "c:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" %MSVC%
   - if defined MSVC pacman --noconfirm -Rsc mingw-w64-%CPU%-gcc gcc
-  - bash -c "sed -i 's/^SigLevel.*/SigLevel = Never/' /etc/pacman.conf"
+  - bash -c "python3 -c \"import re; f='/etc/pacman.conf'; open(f,'w').write(re.sub(r'SigLevel\s*=\s*\S.*', 'SigLevel = Never', open(f).read()))\""
   - pacman --noconfirm -Syuu
   - pacman --noconfirm -S msys2-keyring
-  - bash -c "sed -i 's/^SigLevel = Never/SigLevel    = Required DatabaseOptional/' /etc/pacman.conf"
+  - bash -c "python3 -c \"import re; f='/etc/pacman.conf'; open(f,'w').write(re.sub(r'SigLevel\s*=\s*Never', 'SigLevel = Required DatabaseOptional', open(f).read()))\""
   - pacman --noconfirm -Syuu
   - pacman --noconfirm -S autoconf