}

	for _, key := range extraEnvKeys {
		if val, ok := os.LookupEnv(key); ok {
			env = append(env, key+"="+val)
		}
	}

	return env, nil
}

var extraEnvKeys = []string{
	"SYSTEMROOT",         // must be preserved on Windows to find DLLs; golang.org/issue/25210
	"WINDIR",             // must be preserved on Windows to be able to run PowerShell command; golang.org/issue/30711

		// This approach works with tzres.dll but may have to be revised
		// in the future to allow callers to provide custom search paths.

		var s string
		s, err = ExpandString("%SystemRoot%\\system32\\")
		if err != nil {
			return "", err
		}
		pdir, err = syscall.UTF16PtrFromString(s)
		if err != nil {
			return "", err
		}

				break
			}
		}
		if found {
			return sd
		}
		// In a self-hosted iOS build the above files might
		// not exist. Look for system files instead below.
	case "windows":
		return &sysDir{
			Getenv("SystemRoot") + "\\system32\\drivers\\etc",
			[]string{
				"networks",
				"protocol",
				"services",
			},
		}
	case "plan9":
		return &sysDir{
			"/lib/ndb",
			[]string{
				"common",