diff --git a/app/lua/lauxlib.c b/app/lua/lauxlib.c
index fedd7c56..e9f8f30a 100644
--- a/app/lua/lauxlib.c
+++ b/app/lua/lauxlib.c
@@ -659,13 +659,19 @@ typedef struct LoadFSF {
 static const char *getFSF (lua_State *L, void *ud, size_t *size) {
   LoadFSF *lf = (LoadFSF *)ud;
   (void)L;
+
+  if (L == NULL && size == NULL) // Direct mode check
+    return NULL;
+
   if (lf->extraline) {
     lf->extraline = 0;
     *size = 1;
     return "\n";
   }
+
   if (fs_eof(lf->f)) return NULL;
   *size = fs_read(lf->f, lf->buff, sizeof(lf->buff));
+
   return (*size > 0) ? lf->buff : NULL;
 }
 
diff --git a/lua_modules/ds18b20/ds18b20.lua b/lua_modules/ds18b20/ds18b20.lua
index c31addcf..138c10da 100644
--- a/lua_modules/ds18b20/ds18b20.lua
+++ b/lua_modules/ds18b20/ds18b20.lua
@@ -3,6 +3,7 @@
 -- NODEMCU TEAM
 -- LICENCE: http://opensource.org/licenses/MIT
 -- Vowstar <vowstar@nodemcu.com>
+-- 2015/02/14 sza2 <sza2trash@gmail.com> Fix for negative values
 --------------------------------------------------------------------------------
 
 -- Set module name as parameter of require
@@ -96,12 +97,16 @@ function readNumber(addr, unit)
       crc = ow.crc8(string.sub(data,1,8))
       -- print("CRC="..crc)
       if (crc == data:byte(9)) then
+        t = (data:byte(1) + data:byte(2) * 256)
+        if (t > 32767) then
+          t = t - 65536
+        end
         if(unit == nil or unit == C) then
-          t = (data:byte(1) + data:byte(2) * 256) * 625
+          t = t * 625
         elseif(unit == F) then
-          t = (data:byte(1) + data:byte(2) * 256) * 1125 + 320000
+          t = t * 1125 + 320000
         elseif(unit == K) then
-          t = (data:byte(1) + data:byte(2) * 256) * 625 + 2731500
+          t = t * 625 + 2731500
         else
           return nil
         end