diff --git a/Matrix.hs b/Matrix.hs
index 1c4983b..febbd0b 100644
--- a/Matrix.hs
+++ b/Matrix.hs
@@ -1,8 +1,8 @@
 module Matrix where
 import Data.List  (intercalate)
 
-data Mat a = Mat [[a]]
-type Pos  = (Int, Int)
+newtype Mat a = Mat [[a]]
+type Pos = (Int, Int)
 
 instance Functor Mat where
   fmap f (Mat m) = Mat ((map . map) f m)