diff --git a/DiskFile.c b/DiskFile.c
index 0201093e..59e12668 100644
--- a/DiskFile.c
+++ b/DiskFile.c
@@ -80,6 +80,6 @@ void torch_DiskFile_init(lua_State *L)
   luaT_newmetatable(L, "torch.DiskFile", "torch.File",
                     torch_DiskFile_new, torch_DiskFile_free, NULL);
   
-  luaL_register(L, NULL, torch_DiskFile__);
+  luaT_setfuncs(L, torch_DiskFile__, 0);
   lua_pop(L, 1);
 }
diff --git a/FFI.lua b/FFI.lua
index b35770c4..1780ee89 100644
--- a/FFI.lua
+++ b/FFI.lua
@@ -1,7 +1,5 @@
-if jit then
-
-   local ffi = require 'ffi'
-
+local ok, ffi = pcall(require, 'ffi')
+if ok then
    local Real2real = {
       Byte='unsigned char',
       Char='char',
diff --git a/File.c b/File.c
index e2f8e425..3a463752 100644
--- a/File.c
+++ b/File.c
@@ -199,6 +199,6 @@ static const struct luaL_Reg torch_File__ [] = {
 void torch_File_init(lua_State *L)
 {
   luaT_newmetatable(L, "torch.File", NULL, NULL, NULL, NULL);
-  luaL_register(L, NULL, torch_File__);
+  luaT_setfuncs(L, torch_File__, 0);
   lua_pop(L, 1);
 }
diff --git a/File.lua b/File.lua
index 6ce18000..1b86171b 100644
--- a/File.lua
+++ b/File.lua
@@ -19,7 +19,11 @@ local TYPE_TABLE    = 3
 local TYPE_TORCH    = 4
 local TYPE_BOOLEAN  = 5
 local TYPE_FUNCTION = 6
-local TYPE_RECUR_FUNCTION = 7
+local TYPE_RECUR_FUNCTION = 8
+local LEGACY_TYPE_RECUR_FUNCTION = 7
+
+-- Lua 5.2 compatibility
+local loadstring = loadstring or load
 
 function File:isWritableObject(object)
    local typename = type(object)
@@ -138,7 +142,8 @@ function File:writeObject(object)
                counter = counter + 1
                local name,value = debug.getupvalue(object, counter)
                if not name then break end
-               table.insert(upvalues, value)
+               if name == '_ENV' then value = nil end
+               table.insert(upvalues, {name=name, value=value})
             end
             local dumped = string.dump(object)
             local stringStorage = torch.CharStorage():string(dumped)
@@ -214,7 +219,7 @@ function File:readObject()
           debug.setupvalue(func, index, upvalue)
        end
        return func
-   elseif typeidx == TYPE_TABLE or typeidx == TYPE_TORCH or typeidx == TYPE_RECUR_FUNCTION then
+   elseif typeidx == TYPE_TABLE or typeidx == TYPE_TORCH or typeidx == TYPE_RECUR_FUNCTION or typeidx == LEGACY_TYPE_RECUR_FUNCTION then
       -- read the index
       local index = self:readInt()
 
@@ -225,16 +230,22 @@ function File:readObject()
       end
 
       -- otherwise read it
-      if typeidx == TYPE_RECUR_FUNCTION then
-        local size = self:readInt()
-        local dumped = self:readChar(size):string()
-        local func = loadstring(dumped)
-        objects[index] = func
-        local upvalues = self:readObject()
-        for index,upvalue in ipairs(upvalues) do
-           debug.setupvalue(func, index, upvalue)
-        end
-        return func
+      if typeidx == TYPE_RECUR_FUNCTION or typeidx == LEGACY_TYPE_RECUR_FUNCTION then
+         local size = self:readInt()
+         local dumped = self:readChar(size):string()
+         local func = loadstring(dumped)
+         objects[index] = func
+         local upvalues = self:readObject()
+         for index,upvalue in ipairs(upvalues) do
+            if typeidx == LEGACY_TYPE_RECUR_FUNCTION then
+               debug.setupvalue(func, index, upvalue)
+            elseif upvalue.name == '_ENV' then
+               debug.setupvalue(func, index, _ENV)
+            else
+               debug.setupvalue(func, index, upvalue.value)
+            end
+         end
+         return func
       elseif typeidx == TYPE_TORCH then
          local version, className, versionNumber
          version = self:readChar(self:readInt()):string()
diff --git a/Generator.c b/Generator.c
index 7caf0ce1..06ec6d00 100644
--- a/Generator.c
+++ b/Generator.c
@@ -24,6 +24,6 @@ void torch_Generator_init(lua_State *L)
 {
   luaT_newmetatable(L, torch_Generator, NULL,
                     torch_Generator_new, torch_Generator_free, torch_Generator_factory);
-  luaL_register(L, NULL, torch_Generator_table_);
+  luaT_setfuncs(L, torch_Generator_table_, 0);
   lua_pop(L, 1);
 }
diff --git a/MemoryFile.c b/MemoryFile.c
index a153e207..114dbc49 100644
--- a/MemoryFile.c
+++ b/MemoryFile.c
@@ -56,6 +56,6 @@ void torch_MemoryFile_init(lua_State *L)
 {
   luaT_newmetatable(L, "torch.MemoryFile", "torch.File",
                     torch_MemoryFile_new, torch_MemoryFile_free, NULL);
-  luaL_register(L, NULL, torch_MemoryFile__);
+  luaT_setfuncs(L, torch_MemoryFile__, 0);
   lua_pop(L, 1);
 }
diff --git a/PipeFile.c b/PipeFile.c
index b18f1642..a47c90d1 100644
--- a/PipeFile.c
+++ b/PipeFile.c
@@ -38,6 +38,6 @@ void torch_PipeFile_init(lua_State *L)
 {
   luaT_newmetatable(L, "torch.PipeFile", "torch.DiskFile",
                     torch_PipeFile_new, torch_PipeFile_free, NULL);
-  luaL_register(L, NULL, torch_PipeFile__);
+  luaT_setfuncs(L, torch_PipeFile__, 0);
   lua_pop(L, 1);
 }
diff --git a/Tensor.lua b/Tensor.lua
index fded57e7..cf1d9b7e 100644
--- a/Tensor.lua
+++ b/Tensor.lua
@@ -7,6 +7,9 @@ local Tensor = {}
 -- types
 local types = {'Byte', 'Char', 'Short', 'Int', 'Long', 'Float', 'Double'}
 
+-- Lua 5.2 compatibility
+local log10 = math.log10 or function(x) return math.log(x, 10) end
+
 -- tostring() functions for Tensor and Storage
 local function Storage__printformat(self)
    if self:size() == 0 then 
@@ -25,13 +28,13 @@ local function Storage__printformat(self)
    local tensor = torch.DoubleTensor(torch.DoubleStorage(self:size()):copy(self), 1, self:size()):abs()
    local expMin = tensor:min()
    if expMin ~= 0 then
-      expMin = math.floor(math.log10(expMin)) + 1
+      expMin = math.floor(log10(expMin)) + 1
    else
       expMin = 1
    end
    local expMax = tensor:max()
    if expMax ~= 0 then
-      expMax = math.floor(math.log10(expMax)) + 1
+      expMax = math.floor(log10(expMax)) + 1
    else
       expMax = 1
    end
diff --git a/TensorMath.lua b/TensorMath.lua
index 121c5061..52280fa2 100644
--- a/TensorMath.lua
+++ b/TensorMath.lua
@@ -120,7 +120,8 @@ local function wrap(...)
          end
       end
    end
-   method:wrap(unpack(args))
+   local unpack = unpack or table.unpack
+    method:wrap(unpack(args))
 end
 
 local reals = {ByteTensor='unsigned char',
@@ -1133,12 +1134,12 @@ static void torch_TensorMath_init(lua_State *L)
   luaT_pushmetatable(L, "torch.Tensor");
 
   /* register methods */
-  luaL_register(L, NULL, m_torch_TensorMath__);
+  luaT_setfuncs(L, m_torch_TensorMath__, 0);
 
   /* register functions into the "torch" field of the tensor metaclass */
   lua_pushstring(L, "torch");
   lua_newtable(L);
-  luaL_register(L, NULL, torch_TensorMath__);
+  luaT_setfuncs(L, torch_TensorMath__, 0);
   lua_rawset(L, -3);
   lua_pop(L, 1);
 }
@@ -1157,7 +1158,7 @@ void torch_TensorMath_init(lua_State *L)
   torch_LongTensorMath_init(L);
   torch_FloatTensorMath_init(L);
   torch_DoubleTensorMath_init(L);
-  luaL_register(L, NULL, torch_TensorMath__);
+  luaT_setfuncs(L, torch_TensorMath__, 0);
 }
 ]])
 
diff --git a/Timer.c b/Timer.c
index 152ff75d..96f792a4 100644
--- a/Timer.c
+++ b/Timer.c
@@ -165,6 +165,6 @@ static const struct luaL_Reg torch_Timer__ [] = {
 void torch_Timer_init(lua_State *L)
 {
   luaT_newmetatable(L, "torch.Timer", NULL, torch_Timer_new, torch_Timer_free, NULL);
-  luaL_register(L, NULL, torch_Timer__);
+  luaT_setfuncs(L, torch_Timer__, 0);
   lua_pop(L, 1);
 }
diff --git a/generic/Storage.c b/generic/Storage.c
index 98fad343..8022e530 100644
--- a/generic/Storage.c
+++ b/generic/Storage.c
@@ -273,7 +273,7 @@ void torch_Storage_(init)(lua_State *L)
 {
   luaT_newmetatable(L, torch_Storage, NULL,
                     torch_Storage_(new), torch_Storage_(free), torch_Storage_(factory));
-  luaL_register(L, NULL, torch_Storage_(_));
+  luaT_setfuncs(L, torch_Storage_(_), 0);
   lua_pop(L, 1);
 }
 
diff --git a/generic/Tensor.c b/generic/Tensor.c
index e5f03a3a..680c7d17 100644
--- a/generic/Tensor.c
+++ b/generic/Tensor.c
@@ -1278,7 +1278,7 @@ void torch_Tensor_(init)(lua_State *L)
 {
   luaT_newmetatable(L, torch_Tensor, NULL,
                     torch_Tensor_(new), torch_Tensor_(free), torch_Tensor_(factory));
-  luaL_register(L, NULL, torch_Tensor_(_));
+  luaT_setfuncs(L, torch_Tensor_(_), 0);
   lua_pop(L, 1);
 }
 
diff --git a/generic/TensorOperator.c b/generic/TensorOperator.c
index 6acb8f4f..f6fe4f1f 100644
--- a/generic/TensorOperator.c
+++ b/generic/TensorOperator.c
@@ -166,7 +166,7 @@ static const struct luaL_Reg torch_TensorOperator_(_) [] = {
 void torch_TensorOperator_(init)(lua_State *L)
 {
   luaT_pushmetatable(L, torch_Tensor);
-  luaL_register(L, NULL, torch_TensorOperator_(_));
+  luaT_setfuncs(L, torch_TensorOperator_(_), 0);
   lua_pop(L, 1);
 }
 
diff --git a/init.c b/init.c
index 4d953f60..ad2b257d 100644
--- a/init.c
+++ b/init.c
@@ -56,7 +56,7 @@ int luaopen_libtorch(lua_State *L)
 
   lua_newtable(L);
   lua_pushvalue(L, -1);
-  lua_setfield(L, LUA_GLOBALSINDEX, "torch");
+  lua_setglobal(L, "torch");
 
   torch_File_init(L);
 
diff --git a/init.lua b/init.lua
index 9480b775..76e08d07 100644
--- a/init.lua
+++ b/init.lua
@@ -6,6 +6,9 @@
 if not string.gfind then
     string.gfind = string.gmatch
 end
+if not table.unpack then
+    table.unpack = unpack
+end
 
 require "paths"
 paths.require "libtorch"
diff --git a/lib/luaT/luaT.c b/lib/luaT/luaT.c
index 7b85ce3b..ee74c929 100644
--- a/lib/luaT/luaT.c
+++ b/lib/luaT/luaT.c
@@ -45,6 +45,24 @@ void luaT_free(lua_State *L, void *ptr)
   free(ptr);
 }
 
+void luaT_setfuncs(lua_State *L, const luaL_Reg *l, int nup)
+{
+#if LUA_VERSION_NUM == 501
+  luaL_checkstack(L, nup+1, "too many upvalues");
+  for (; l->name != NULL; l++) {  /* fill the table with given functions */
+    int i;
+    lua_pushstring(L, l->name);
+    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
+      lua_pushvalue(L, -(nup+1));
+    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
+    lua_settable(L, -(nup + 3));
+  }
+  lua_pop(L, nup);  /* remove upvalues */
+#else
+  luaL_setfuncs(L, l, nup);
+#endif
+}
+
 void luaT_stackdump(lua_State *L)
 {
   int i;
@@ -159,11 +177,16 @@ const char *luaT_typenameid(lua_State *L, const char *tname)
 }
 
 static const char cdataname[] = ""
-  "local _, ffi = pcall(require, 'ffi')\n"
-  "if ffi then\n"
+  "local ok, ffi = pcall(require, 'ffi')\n"
+  "if ok then\n"
   "  local id2name = {}\n"
   "  return function(cdata, name)\n"
-  "    local id = tonumber(ffi.typeof(cdata))\n"
+  "    local id\n"
+  "    if jit then\n"
+  "      id = tonumber(ffi.typeof(cdata))\n"
+  "    else\n"
+  "      id = tostring(ffi.typeof(cdata))\n"
+  "    end\n"
   "    if id then\n"
   "      if name then\n"
   "        id2name[id] = name\n"
@@ -208,9 +231,47 @@ static const char* luaT_cdataname(lua_State *L, int ud, const char *tname)
   return tname;
 }
 
+static void* CDATA_MT_KEY = &CDATA_MT_KEY;
+static const char cdatamt[] = ""
+  "local ok, ffi = pcall(require, 'ffi')\n"
+  "if ok and not jit then\n"
+  "  return ffi.debug().cdata_mt\n"
+  "else\n"
+  "  return {}\n"
+  "end\n";
+
+static int luaT_iscdata(lua_State *L, int ud)
+{
+  int type = lua_type(L, ud);
+  if(type == 10)
+    return 1;
+  if(type != LUA_TUSERDATA)
+    return 0;
+  if(!lua_getmetatable(L, ud))
+    return 0;
+
+  lua_pushlightuserdata(L, CDATA_MT_KEY);
+  lua_rawget(L, LUA_REGISTRYINDEX);
+  if (lua_isnil(L, -1))
+  {
+    // initialize cdata metatable
+    lua_pop(L, 1);
+    if(luaL_dostring(L, cdatamt))
+      luaL_error(L, "internal error (could not load cdata mt): %s", lua_tostring(L, -1));
+
+    lua_pushlightuserdata(L, CDATA_MT_KEY);
+    lua_pushvalue(L, -2);
+    lua_rawset(L, LUA_REGISTRYINDEX);
+  }
+
+  int iscdata = lua_rawequal(L, -1, -2);
+  lua_pop(L, 2);
+  return iscdata;
+}
+
 const char* luaT_typename(lua_State *L, int ud)
 {
-  if(lua_type(L, ud) == 10)
+  if(luaT_iscdata(L, ud))
     return luaT_cdataname(L, ud, NULL);
   else if(lua_getmetatable(L, ud))
   {
@@ -405,7 +466,7 @@ void luaT_registeratname(lua_State *L, const struct luaL_Reg *methods, const cha
     lua_rawget(L, idx);
   }
 
-  luaL_register(L, NULL, methods);
+  luaT_setfuncs(L, methods, 0);
   lua_pop(L, 1);
 }
 
@@ -451,9 +512,9 @@ int luaT_lua_newmetatable(lua_State *L)
   luaL_argcheck(L, lua_isnoneornil(L, 5) || lua_isfunction(L, 5), 5, "factory function or nil expected");
 
   if(is_in_module)
-    lua_getfield(L, LUA_GLOBALSINDEX, module_name);
+    lua_getglobal(L, module_name);
   else
-    lua_pushvalue(L, LUA_GLOBALSINDEX);
+    lua_pushglobaltable(L);
   if(!lua_istable(L, 6))
     luaL_error(L, "while creating metatable %s: bad argument #1 (%s is an invalid module name)", tname, module_name);
 
@@ -689,6 +750,8 @@ int luaT_lua_pushudata(lua_State *L)
 
   if(lua_type(L, 1) == 10)
     udata = *((void**)lua_topointer(L, 1));
+  else if(luaT_iscdata(L, 1))
+    udata = ((void**)lua_topointer(L, 1))[4];
   else if(lua_isnumber(L, 1))
     udata = (void*)(long)lua_tonumber(L, 1);
   else
@@ -763,7 +826,21 @@ int luaT_lua_isequal(lua_State *L)
 
 int luaT_lua_pointer(lua_State *L)
 {
-  if(lua_isuserdata(L, 1))
+  if(lua_type(L, 1) == 10) /* luajit cdata */
+  {
+    /* we want the pointer holded by cdata */
+    /* not the pointer on the cdata object */
+    const void* ptr = *((void**)lua_topointer(L, 1));
+    lua_pushnumber(L, (long)(ptr));
+    return 1;
+  }
+  else if (luaT_iscdata(L, 1)) /* luaffi cdata */
+  {
+    void** ptr = (void**)lua_touserdata(L, 1);
+    lua_pushnumber(L, (long)(ptr[4]));
+    return 1;
+  }
+  else if(lua_isuserdata(L, 1))
   {
     void **ptr;
     luaL_argcheck(L, luaT_typename(L, 1), 1, "Torch object expected");
@@ -777,14 +854,6 @@ int luaT_lua_pointer(lua_State *L)
     lua_pushnumber(L, (long)(ptr));
     return 1;
   }
-  else if(lua_type(L, 1) == 10) /* cdata */
-  {
-    /* we want the pointer holded by cdata */
-    /* not the pointer on the cdata object */
-    const void* ptr = *((void**)lua_topointer(L, 1));
-    lua_pushnumber(L, (long)(ptr));
-    return 1;
-  }
   else if(lua_isstring(L, 1))
   {
     const char* ptr = lua_tostring(L, 1);
@@ -802,7 +871,7 @@ int luaT_lua_setenv(lua_State *L)
   if(!lua_isfunction(L, 1) && !lua_isuserdata(L, 1))
     luaL_typerror(L, 1, "function or userdata");
   luaL_checktype(L, 2, LUA_TTABLE);
-  lua_setfenv(L, 1);
+  lua_setuservalue(L, 1);
   return 0;
 }
 
@@ -810,7 +879,9 @@ int luaT_lua_getenv(lua_State *L)
 {
   if(!lua_isfunction(L, 1) && !lua_isuserdata(L, 1))
     luaL_typerror(L, 1, "function or userdata");
-  lua_getfenv(L, 1);
+  lua_getuservalue(L, 1);
+  if (lua_isnil(L, -1))
+    lua_newtable(L);
   return 1;
 }
 
@@ -826,7 +897,7 @@ int luaT_lua_version(lua_State *L)
 {
   luaL_checkany(L, 1);
 
-  if(lua_type(L, 1) == 10)
+  if(luaT_iscdata(L, 1))
   {
     const char *tname = luaT_cdataname(L, 1, NULL);
     if(tname)
diff --git a/lib/luaT/luaT.h b/lib/luaT/luaT.h
index 5e8dd2f6..4c25fc1c 100644
--- a/lib/luaT/luaT.h
+++ b/lib/luaT/luaT.h
@@ -32,6 +32,18 @@ extern "C" {
 # define LUAT_API LUA_EXTERNC
 #endif
 
+#if LUA_VERSION_NUM == 501
+# define lua_pushglobaltable(L) lua_pushvalue(L, LUA_GLOBALSINDEX)
+# define lua_setuservalue lua_setfenv
+# define lua_getuservalue lua_getfenv
+#else
+# define lua_objlen lua_rawlen
+static int luaL_typerror(lua_State *L, int narg, const char *tname)
+{
+  return luaL_error(L, "%s expected, got %s", tname, luaL_typename(L, narg));
+}
+#endif
+
 
 /* C functions */
 
@@ -39,6 +51,8 @@ LUAT_API void* luaT_alloc(lua_State *L, long size);
 LUAT_API void* luaT_realloc(lua_State *L, void *ptr, long size);
 LUAT_API void luaT_free(lua_State *L, void *ptr);
 
+LUAT_API void luaT_setfuncs(lua_State *L, const luaL_Reg *l, int nup);
+
 LUAT_API const char* luaT_newmetatable(lua_State *L, const char *tname, const char *parenttname,
                                        lua_CFunction constructor, lua_CFunction destructor, lua_CFunction factory);
 
diff --git a/random.lua b/random.lua
index 6740866a..a6f0c3da 100644
--- a/random.lua
+++ b/random.lua
@@ -46,7 +46,7 @@ void torch_random_init(lua_State *L)
   torch_Generator_init(L);
   torch_Generator_new(L);
   lua_setfield(L, -2, "_gen");
-  luaL_register(L, NULL, random__);
+  luaT_setfuncs(L, random__, 0);
 }
 ]])
 
diff --git a/test/test.lua b/test/test.lua
index 8eb68b92..a9fe7668 100644
--- a/test/test.lua
+++ b/test/test.lua
@@ -5,6 +5,10 @@ local torchtest = {}
 local msize = 100
 local precision
 
+-- Lua 5.2 compatibility
+local loadstring = loadstring or load
+local unpack = unpack or table.unpack
+
 local function maxdiff(x,y)
    local d = x-y
    if x:type() == 'torch.DoubleTensor' or x:type() == 'torch.FloatTensor' then
diff --git a/test/test_writeObject.lua b/test/test_writeObject.lua
index 36be49a7..90392f95 100644
--- a/test/test_writeObject.lua
+++ b/test/test_writeObject.lua
@@ -28,6 +28,28 @@ function tests.test_can_write_a_nil_closure()
   myTester:assert(copyClosure() == closure(), 'the closures should give same output')
 end
 
+function tests.test_nil_upvalues_in_closure()
+  local a = 1
+  local b
+  local c = 2
+  local function closure()
+    if not b then return c end
+    return a
+  end
+
+  local copyClosure = serializeAndDeserialize(closure)
+  myTester:assert(copyClosure() == closure(), 'the closures should give same output')
+end
+
+function tests.test_global_function_in_closure()
+  local x = "5"
+  local function closure(str)
+    return tonumber(str .. x)
+  end
+
+  local copyClosure = serializeAndDeserialize(closure)
+  myTester:assert(copyClosure("3") == closure("3"), 'the closures should give same output')
+end
 
 function tests.test_a_recursive_closure()
   local foo
diff --git a/test/timeSort.lua b/test/timeSort.lua
index 3d798979..baa0b7de 100644
--- a/test/timeSort.lua
+++ b/test/timeSort.lua
@@ -10,7 +10,8 @@ cmd:option('-r', 20, 'Number of repetitions')
 
 local options = cmd:parse(arg or {})
 function main()
-    local pow10 = torch.linspace(1,math.log10(options.N), options.p)
+    local log10 = math.log10 or function(x) return math.log(x, 10) end
+    local pow10 = torch.linspace(1,log10(options.N), options.p)
     local num_sizes = options.p
     local num_reps = options.r
 
@@ -128,11 +129,11 @@ function main()
     gnuplot.xlabel('N')
     gnuplot.ylabel('Speed-up Factor (s)')
     gnuplot.figprint('benchmarkRatio.png')
-    
+
     torch.save('benchmark.t7', {
                new_rnd=new_rnd,
                new_srt=new_srt,
-               new_cst=new_cst, 
+               new_cst=new_cst,
                old_rnd=old_rnd,
                old_srt=old_srt,
                old_cst=old_cst,
diff --git a/utils.c b/utils.c
index aa5603a3..acc77f7b 100644
--- a/utils.c
+++ b/utils.c
@@ -113,7 +113,7 @@ static int torch_lua_getdefaulttensortype(lua_State *L)
 
 const char* torch_getdefaulttensortype(lua_State *L)
 {
-  lua_getfield(L, LUA_GLOBALSINDEX, "torch");
+  lua_getglobal(L, "torch");
   if(lua_istable(L, -1))
   {
     lua_getfield(L, -1, "Tensor");
@@ -214,5 +214,5 @@ static const struct luaL_Reg torch_utils__ [] = {
 
 void torch_utils_init(lua_State *L)
 {
-  luaL_register(L, NULL, torch_utils__);
+  luaT_setfuncs(L, torch_utils__, 0);
 }