diff --git a/code/asm/vm_x86_64.asm b/code/asm/vm_x86_64.asm
index f39289ec..f84eb8f8 100644
--- a/code/asm/vm_x86_64.asm
+++ b/code/asm/vm_x86_64.asm
@@ -28,19 +28,35 @@
 ; Call to compiled code after setting up the register environment for the VM
 ; prototype:
 ; uint8_t qvmcall64(int *programStack, int *opStack, intptr_t *instructionPointers, byte *dataBase);
+;
+; This call-stub has its own custom calling convention due to pushing all non-volatile registers
+; to the stack. The game uses set/longjmp which on Windows uses "RtlUnwindEx" to unwind the callstack.
+; This function cannot be unwound by default due to the custom calling convention.
+; To allow unwinding, we need to add custom SEH unwind data to the function.
 
-qvmcall64 PROC
+qvmcall64 PROC FRAME
   push r12							; push all non-volatile registers to stack
+  .pushreg r12
   push r13
+  .pushreg r13
   push r14
+  .pushreg r14
   push r15
+  .pushreg r15
   push rdi
+  .pushreg rdi
   push rsi
+  .pushreg rsi
   push rbx
+  .pushreg rbx
   push rbp
+  .pushreg rbp
   
   ; need to save pointer in rcx so we can write back the programData value to caller
   push rcx
+  .pushreg rcx
+  
+  .endprolog						; custom unwind data ends here
 
   ; registers r8 and r9 have correct value already thanx to __fastcall
   xor rbx, rbx						; opStackOfs starts out being 0