diff --git a/bochs/cpu/i387.h b/bochs/cpu/i387.h
index 1a4249e37..6959e2689 100644
--- a/bochs/cpu/i387.h
+++ b/bochs/cpu/i387.h
@@ -1,5 +1,5 @@
 /////////////////////////////////////////////////////////////////////////
-// $Id: i387.h,v 1.31 2005-06-09 17:42:34 vruppert Exp $
+// $Id: i387.h,v 1.32 2006-06-08 19:56:30 sshwarts Exp $
 /////////////////////////////////////////////////////////////////////////
 //
 //   Copyright (c) 2004 Stanislav Shwartsman
@@ -117,13 +117,13 @@ BX_CPP_INLINE void i387_t::FPU_settagi(int tag, int stnr)
 
 BX_CPP_INLINE void i387_t::FPU_push(void)
 {
-  tos--;
+  tos = (tos - 1) & 7;
 }
 
 BX_CPP_INLINE void i387_t::FPU_pop(void)
 {
-  twd |= 3 << ((tos & 7)*2);
-  tos++;
+  twd |= 3 << (tos*2);
+  tos = (tos + 1) & 7;
 }
 
 BX_CPP_INLINE void i387_t::FPU_save_regi(floatx80 reg, int tag, int stnr)