diff --git a/FFI.lua b/FFI.lua
index 1780ee89..904302aa 100644
--- a/FFI.lua
+++ b/FFI.lua
@@ -1,4 +1,19 @@
 local ok, ffi = pcall(require, 'ffi')
+
+local function checkArgument(condition, fn, ud, msg, level)
+   local level = level or 3
+   if not condition then
+      error("bad argument #" .. ud .. " to '" .. fn .. "' (" .. msg .. ")", level)
+   end
+end
+
+local function checkArgumentType(expected, actual, fn, ud, level)
+   local level = level or 3
+   if expected ~= actual then
+      checkArgument(false, fn, ud, expected .. " expected, got " .. actual, level + 1)
+   end
+end
+
 if ok then
    local Real2real = {
       Byte='unsigned char',
@@ -115,6 +130,9 @@ typedef struct THRealTensor
       rawset(Tensor,
              "map",
              function(self, src, func)
+                checkArgument(torch.isTensor(src), "map", 1, "tensor expected")
+                checkArgumentType(self:type(), src:type(), "map", 1)
+
                 if self:isContiguous() and src:isContiguous() and self.data and src.data then
                    local self_d = self:data()
                    local src_d = src:data()
@@ -136,6 +154,11 @@ typedef struct THRealTensor
       rawset(Tensor,
              "map2",
              function(self, src1, src2, func)
+                checkArgument(torch.isTensor(src1), "map", 1, "tensor expected")
+                checkArgument(torch.isTensor(src2), "map", 2, "tensor expected")
+                checkArgumentType(self:type(), src1:type(), "map", 1)
+                checkArgumentType(self:type(), src2:type(), "map", 2)
+
                 if self:isContiguous() and src1:isContiguous() and src2:isContiguous() and self.data and src1.data and src2.data then
                    local self_d = self:data()
                    local src1_d = src1:data()