diff --git a/luprex/eris-master/src/lapi.c b/luprex/eris-master/src/lapi.c
index 6b3d1181..a7664702 100644
--- a/luprex/eris-master/src/lapi.c
+++ b/luprex/eris-master/src/lapi.c
@@ -909,15 +909,15 @@ LUA_API void lua_setflagbits (lua_State *L, int idx, unsigned short bits) {
   lua_unlock(L);
 }
 
-LUA_API void lua_modflagbits (lua_State *L, int idx, unsigned short set, unsigned short clear) {
+LUA_API void lua_modflagbits (lua_State *L, int idx, unsigned short clear, unsigned short set) {
   TValue *obj;
   Table *tab;
   lua_lock(L);
   obj = index2addr(L, idx);
   api_check(L, ttistable(obj), "table expected");
   tab = hvalue(obj);
-  tab->flagbits |= set;
   tab->flagbits &= (~clear);
+  tab->flagbits |= set;
   lua_unlock(L);
 }
 
diff --git a/luprex/eris-master/src/lua.h b/luprex/eris-master/src/lua.h
index 1022c754..a78a5e1b 100644
--- a/luprex/eris-master/src/lua.h
+++ b/luprex/eris-master/src/lua.h
@@ -246,7 +246,7 @@ LUA_API void           (lua_rawsetp) (lua_State *L, int idx, const void *p);
 LUA_API int            (lua_setmetatable) (lua_State *L, int objindex);
 LUA_API void           (lua_setuservalue) (lua_State *L, int idx);
 LUA_API void           (lua_setflagbits) (lua_State *L, int idx, unsigned short bits);
-LUA_API void           (lua_modflagbits) (lua_State *L, int idx, unsigned short set, unsigned short clear);
+LUA_API void           (lua_modflagbits) (lua_State *L, int idx, unsigned short clear, unsigned short set);
 LUA_API unsigned short (lua_getflagbits) (lua_State *L, int idx);
 
 /*