diff --git a/.github/workflows/windows-build.yml b/.github/workflows/windows-build.yml
index 1b1eda59..16596691 100644
--- a/.github/workflows/windows-build.yml
+++ b/.github/workflows/windows-build.yml
@@ -92,10 +92,14 @@ jobs:
           $luaArchive = "lua-$luaVersion.tar.gz"
           $luaUrl = "https://www.lua.org/ftp/$luaArchive"
           $luaDir = "lua-$luaVersion"
-          $luaExtractRoot = Join-Path $env:RUNNER_TEMP $luaDir
-          Invoke-WebRequest $luaUrl -OutFile (Join-Path $env:RUNNER_TEMP $luaArchive)
-          & 7z.exe x (Join-Path $env:RUNNER_TEMP $luaArchive) -o$env:RUNNER_TEMP | Out-Null
-          & 7z.exe x (Join-Path $env:RUNNER_TEMP "lua-$luaVersion.tar") -o$env:RUNNER_TEMP | Out-Null
+          $runnerTemp = $env:RUNNER_TEMP
+          if (-not $runnerTemp) { $runnerTemp = $env:TEMP }
+          if (-not $runnerTemp) { throw "RUNNER_TEMP/TEMP is not set." }
+          New-Item -Path $runnerTemp -ItemType Directory -Force | Out-Null
+          $luaExtractRoot = Join-Path $runnerTemp $luaDir
+          Invoke-WebRequest $luaUrl -OutFile (Join-Path $runnerTemp $luaArchive)
+          & 7z.exe x (Join-Path $runnerTemp $luaArchive) -o$runnerTemp | Out-Null
+          & 7z.exe x (Join-Path $runnerTemp "lua-$luaVersion.tar") -o$runnerTemp | Out-Null
 
           $luaBuildArch = if ($gvsPlatform -eq "x86") { "x86" } else { "amd64" }
           cmd /c "call `"C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Common7\Tools\VsDevCmd.bat`" -arch=$luaBuildArch && cd /d `"$luaExtractRoot\src`" && nmake -f Makefile.msc"