diff --git a/appveyor.yml b/appveyor.yml
index dca48315..cab9f65c 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -13,7 +13,7 @@ deploy: true
 
 install:
   - ps: Start-FileDownload "http://libgd.blob.core.windows.net/mingw/x86_64-4.9.1-release-posix-seh-rt_v3-rev1.7z"
-  - ps: 7z x -o C:\x86_64-4.9.1-release-posix-seh-rt_v3-rev1.7z | out-null
+  - ps: 7z x -oC:\ x86_64-4.9.1-release-posix-seh-rt_v3-rev1.7z | out-null
   - echo %PATH%
   - echo %GOPATH%
   - go version