diff --git a/lapi.c b/lapi.c
index 71a9124a..5edb9fcf 100644
--- a/lapi.c
+++ b/lapi.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.174 2013/04/25 13:52:49 roberto Exp roberto $
+** $Id: lapi.c,v 2.175 2013/04/26 15:39:25 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -271,7 +271,7 @@ LUA_API int lua_isinteger (lua_State *L, int idx) {
 
 
 LUA_API int lua_isnumber (lua_State *L, int idx) {
-  TValue n;
+  lua_Number n;
   const TValue *o = index2addr(L, idx);
   return tonumber(o, &n);
 }
@@ -339,11 +339,11 @@ LUA_API int lua_compare (lua_State *L, int index1, int index2, int op) {
 
 
 LUA_API lua_Number lua_tonumberx (lua_State *L, int idx, int *isnum) {
-  TValue n;
+  lua_Number n;
   const TValue *o = index2addr(L, idx);
   if (tonumber(o, &n)) {
     if (isnum) *isnum = 1;
-    return nvalue(o);
+    return n;
   }
   else {
     if (isnum) *isnum = 0;
@@ -353,7 +353,7 @@ LUA_API lua_Number lua_tonumberx (lua_State *L, int idx, int *isnum) {
 
 
 LUA_API lua_Integer lua_tointegerx (lua_State *L, int idx, int *isnum) {
-  TValue n;
+  lua_Number n;
   const TValue *o = index2addr(L, idx);
   if (ttisinteger(o)) {
     if (isnum) *isnum = 1;
@@ -361,8 +361,7 @@ LUA_API lua_Integer lua_tointegerx (lua_State *L, int idx, int *isnum) {
   }
   else if (tonumber(o, &n)) {
     lua_Integer res;
-    lua_Number num = nvalue(o);
-    lua_number2integer(res, num);
+    lua_number2integer(res, n);
     if (isnum) *isnum = 1;
     return res;
   }
@@ -374,12 +373,11 @@ LUA_API lua_Integer lua_tointegerx (lua_State *L, int idx, int *isnum) {
 
 
 LUA_API lua_Unsigned lua_tounsignedx (lua_State *L, int idx, int *isnum) {
-  TValue n;
+  lua_Number n;
   const TValue *o = index2addr(L, idx);
   if (tonumber(o, &n)) {
     lua_Unsigned res;
-    lua_Number num = nvalue(o);
-    lua_number2unsigned(res, num);
+    lua_number2unsigned(res, n);
     if (isnum) *isnum = 1;
     return res;
   }
diff --git a/ldebug.c b/ldebug.c
index 96d47085..478c642e 100644
--- a/ldebug.c
+++ b/ldebug.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldebug.c,v 2.91 2013/04/25 15:59:42 roberto Exp roberto $
+** $Id: ldebug.c,v 2.92 2013/04/26 13:07:53 roberto Exp roberto $
 ** Debug Interface
 ** See Copyright Notice in lua.h
 */
@@ -525,8 +525,8 @@ l_noret luaG_concaterror (lua_State *L, StkId p1, StkId p2) {
 
 
 l_noret luaG_aritherror (lua_State *L, const TValue *p1, const TValue *p2) {
-  TValue temp;
-  if (luaV_tonumber(p1, &temp) == NULL)
+  lua_Number temp;
+  if (!tonumber(p1, &temp))
     p2 = p1;  /* first operand is wrong */
   luaG_typeerror(L, p2, "perform arithmetic on");
 }
diff --git a/lvm.c b/lvm.c
index d772590d..afe1a8fd 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 2.162 2013/04/25 19:50:02 roberto Exp roberto $
+** $Id: lvm.c,v 2.163 2013/04/26 13:07:53 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -32,19 +32,14 @@
 #define MAXTAGLOOP	100
 
 
-const TValue *luaV_tonumber (const TValue *obj, TValue *n) {
-  lua_Number num;
-  if (ttisfloat(obj)) return obj;
+int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
+  lua_assert(!ttisfloat(obj));
   if (ttisinteger(obj)) {
-    setnvalue(n, cast_num(ivalue(obj)));
-    return n;
-  }
-  if (ttisstring(obj) && luaO_str2d(svalue(obj), tsvalue(obj)->len, &num)) {
-    setnvalue(n, num);
-    return n;
+    *n = cast_num(ivalue(obj));
+    return 1;
   }
   else
-    return NULL;
+    return (ttisstring(obj) && luaO_str2d(svalue(obj), tsvalue(obj)->len, n));
 }
 
 
@@ -337,11 +332,9 @@ lua_Integer luaV_pow (lua_Integer x, lua_Integer y) {
 
 void luaV_arith (lua_State *L, StkId ra, const TValue *rb,
                  const TValue *rc, TMS op) {
-  TValue tempb, tempc;
-  const TValue *b, *c;
-  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
-      (c = luaV_tonumber(rc, &tempc)) != NULL) {
-    lua_Number res = luaO_arith(op - TM_ADD + LUA_OPADD, nvalue(b), nvalue(c));
+  lua_Number b, c;
+  if (tonumber(rb, &b) && tonumber(rc, &c)) {
+    lua_Number res = luaO_arith(op - TM_ADD + LUA_OPADD, b, c);
     setnvalue(ra, res);
   }
   else if (!luaT_callbinTM(L, rb, rc, ra, op))
@@ -841,20 +834,23 @@ void luaV_execute (lua_State *L) {
         }
       )
       vmcase(OP_FORPREP,
-        const TValue *init = ra;
-        const TValue *plimit = ra+1;
-        const TValue *pstep = ra+2;
+        TValue *init = ra;
+        TValue *plimit = ra + 1;
+        TValue *pstep = ra + 2;
         if (ttisinteger(ra) && ttisinteger(ra + 1) && ttisinteger(ra + 2)) {
           setivalue(ra, ivalue(ra) - ivalue(pstep));
         }
         else {  /* try with floats */
-          if (!tonumber(init, ra))
+          lua_Number ninit; lua_Number nlimit; lua_Number nstep;
+          if (!tonumber(init, &ninit))
             luaG_runerror(L, LUA_QL("for") " initial value must be a number");
-          else if (!tonumber(plimit, ra+1))
+          if (!tonumber(plimit, &nlimit))
             luaG_runerror(L, LUA_QL("for") " limit must be a number");
-          else if (!tonumber(pstep, ra+2))
+          setnvalue(plimit, nlimit);
+          if (!tonumber(pstep, &nstep))
             luaG_runerror(L, LUA_QL("for") " step must be a number");
-          setnvalue(ra, luai_numsub(L, fltvalue(ra), fltvalue(pstep)));
+          setnvalue(pstep, nstep);
+          setnvalue(ra, luai_numsub(L, ninit, nstep));
         }
         ci->u.l.savedpc += GETARG_sBx(i);
       )
diff --git a/lvm.h b/lvm.h
index 07235f19..9d0d66ca 100644
--- a/lvm.h
+++ b/lvm.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.h,v 2.19 2013/04/15 15:44:46 roberto Exp roberto $
+** $Id: lvm.h,v 2.20 2013/04/25 19:12:41 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -15,7 +15,8 @@
 
 #define tostring(L,o) (ttisstring(o) || (luaV_tostring(L, o)))
 
-#define tonumber(o,n)	(ttisfloat(o) || (((o) = luaV_tonumber(o,n)) != NULL))
+#define tonumber(o,n) \
+	(ttisfloat(o) ? (*(n) = fltvalue(o), 1) : luaV_tonumber_(o,n))
 
 
 #define luaV_rawequalobj(t1,t2)		luaV_equalobj(NULL,t1,t2)
@@ -24,7 +25,7 @@
 LUAI_FUNC int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2);
 LUAI_FUNC int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r);
 LUAI_FUNC int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r);
-LUAI_FUNC const TValue *luaV_tonumber (const TValue *obj, TValue *n);
+LUAI_FUNC int luaV_tonumber_ (const TValue *obj, lua_Number *n);
 LUAI_FUNC int luaV_tostring (lua_State *L, StkId obj);
 LUAI_FUNC void luaV_gettable (lua_State *L, const TValue *t, TValue *key,
                                             StkId val);