diff --git a/vm/callstack.h b/vm/callstack.h
index ff68a8ba26..564dea9738 100644
--- a/vm/callstack.h
+++ b/vm/callstack.h
@@ -1,5 +1,5 @@
 F_FASTCALL void save_callstack_bottom(F_STACK_FRAME *callstack_bottom);
-__attribute__((noinline)) void save_callstack_top(F_STACK_FRAME *callstack_top);
+F_FASTCALL __attribute__((noinline)) void save_callstack_top(F_STACK_FRAME *callstack_top);
 
 #define FIRST_STACK_FRAME(stack) (F_STACK_FRAME *)((stack) + 1)
 
diff --git a/vm/os-windows-nt.c b/vm/os-windows-nt.c
index 8f7513a32a..f6aa314819 100644
--- a/vm/os-windows-nt.c
+++ b/vm/os-windows-nt.c
@@ -29,7 +29,7 @@ long exception_handler(PEXCEPTION_POINTERS pe)
 	CONTEXT *c = (CONTEXT*)pe->ContextRecord;
 
 	if(in_code_heap_p(c->Eip))
-		signal_callstack_top = (void*)c->Esp;
+		signal_callstack_top = (void *)(c->Esp - CELLS);
 	else
 		signal_callstack_top = NULL;