Do not use GetSystemDirectory. Use GetSysPath which is exactly the same as GetWinPath except it gets the System directory.
Code:
Option Explicit

Private Declare Function GetSystemDirectory Lib "kernel32" Alias "GetSystemDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long

Private Const MAX_PATH = 260

Function GetSysPath() As String
    Dim lPos As Long
    
    GetSysPath = String(MAX_PATH, vbNullChar)
    Call GetSystemDirectory(GetSysPath, MAX_PATH)
    
    lPos = InStr(GetSysPath, vbNullChar)
    If lPos > 0 Then GetSysPath = Left(GetSysPath, lPos - 1)
    
    If Not Right(GetSysPath, 1) = "\" Then GetSysPath = GetSysPath & "\"
End Function
Enjoy!

Cool code sections:

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Result:
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