diff --git a/smiti18n/init.lua b/smiti18n/init.lua
index 62b223e..b59ef12 100644
--- a/smiti18n/init.lua
+++ b/smiti18n/init.lua
@@ -161,6 +161,7 @@ local function localizedTranslate(key, loc, data)
 end
 
 local function concat(arr1, arr2)
+  if not arr2 then return arr1 end
   for i = 1, #arr2 do
     arr1[#arr1 + i] = arr2[i]
   end