Julian Ospald
--- a/bootstrap-haskell.ps1
+++ b/bootstrap-haskell.ps1
+
+Write-Host 'Unsetting GHCUP_INSTALL_BASE_PREFIX' -ForegroundColor Green
+[Environment]::SetEnvironmentVariable('GHCUP_INSTALL_BASE_PREFIX', $null, [System.EnvironmentVariableTarget]::User)
+
+$ghcupMsys2 = [System.Environment]::GetEnvironmentVariable('GHCUP_MSYS2', 'user')
+$GhcupBasePrefixEnv = [System.Environment]::GetEnvironmentVariable('GHCUP_INSTALL_BASE_PREFIX', 'user')
+
+if ($ghcupMsys2) {
+  $msys2Dir = [IO.Path]::GetFullPath($ghcupMsys2)
+  $baseDir = [IO.Path]::GetFullPath('{0}\ghcup' -f $GhcupBasePrefixEnv)
+
+  if ($msys2Dir.StartsWith($baseDir)) {
+    Write-Host 'Unsetting GHCUP_MSYS2' -ForegroundColor Green
+    [Environment]::SetEnvironmentVariable('GHCUP_MSYS2', $null, [System.EnvironmentVariableTarget]::User)
+  } else {
+    Write-Host ('GHCUP_MSYS2 env variable is set to a non-standard location {0}. Environment variable not unset. Uninstall manually.' -f $msys2Dir) -ForegroundColor Magenta