diff --git a/rtl/go32v2/system.pp b/rtl/go32v2/system.pp
index 44c8bb2a81..bdf8c23334 100644
--- a/rtl/go32v2/system.pp
+++ b/rtl/go32v2/system.pp
@@ -642,8 +642,12 @@ end;
 var
   temp_int : tseginfo;
 Begin
-  StackLength := CheckInitialStkLen(InitialStkLen);
+{ v2prt0.as adds 256 bytes to __stkbottom for extra safety during stack
+  checking, so we subtract 256 here in order to calculate StackTop correctly
+  and to ensure that StackLength = StackTop - StackBottom }
+  StackLength := CheckInitialStkLen(InitialStkLen)-256;
   StackBottom := __stkbottom;
+  StackTop := StackBottom + StackLength;
   { To be set if this is a GUI or console application }
   IsConsole := TRUE;
   { To be set if this is a library and not a program  }