diff --git a/rtl/win64/system.pp b/rtl/win64/system.pp
index c004035888..497fdd3ae7 100644
--- a/rtl/win64/system.pp
+++ b/rtl/win64/system.pp
@@ -601,8 +601,8 @@ begin
   GetStartupInfo(@startupinfo);
   { some misc Win32 stuff }
   if not IsLibrary then
-    SysInstance:=getmodulehandle(nil);
-  MainInstance:=SysInstance;
+    FPCSysInstance^:=getmodulehandle(nil);
+  MainInstance:=FPCSysInstance^;
   cmdshow:=startupinfo.wshowwindow;
   { Setup heap and threading, these may be already initialized from TLS callback }
   if not Assigned(CurrentTM.BeginThread) then