diff --git a/appveyor.yml b/appveyor.yml
index 22386ff..9d62224 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -10,7 +10,7 @@ for:
     only:
       - image: Visual Studio 2019
   before_build:
-    - (Get-Content src/engine/main.cpp) -replace '<git-dev>', (git describe) | Set-Content src/engine/main.cpp
+    - ps: (Get-Content src/engine/main.cpp) -replace '<git-dev>', (git describe) | Set-Content src/engine/main.cpp
   build:
     project: src/vcpp/sauerbraten.vcxproj
     verbosity: minimal
@@ -22,7 +22,7 @@ for:
       - image: macOS
   before_build:
     - cd src
-    - sed -i "s/<git-dev>/$(git describe)/" engine/main.cpp
+    - sed -i '' "s/<git-dev>/$(git describe)/" engine/main.cpp
   build_script:
     - make client
   after_build: