diff --git a/lua/flatbuffers/compat.lua b/lua/flatbuffers/compat.lua
new file mode 100644
index 0000000..89c992b
--- /dev/null
+++ b/lua/flatbuffers/compat.lua
@@ -0,0 +1,17 @@
+local m = {}
+
+local getAlignSize
+if _VERSION == "Lua 5.3" then
+    getAlignSize = function(k, size)
+            return ((~k) + 1) & (size - 1)
+        end    
+else
+    getAlignSize = function(self, size, additionalBytes)        
+        local alignsize = bit32.bnot(#self.bytes-self:Head() + additionalBytes) + 1
+        return bit32.band(alignsize,(size - 1))
+    end
+end
+    
+m.GetAlignSize = getAlignSize
+
+return m
\ No newline at end of file