diff --git a/lib/simplify.ml b/lib/simplify.ml
index 13dde28..d11dc15 100644
--- a/lib/simplify.ml
+++ b/lib/simplify.ml
@@ -8,9 +8,7 @@ let rec fold_plus (term : Expression.arith) =
   | Plus (Num m, Num n) -> Num (m + n)
   | Plus (Plus (t, Num m), Num n) -> fold_plus (Plus (t, Num (m + n)))
   | _ as t -> t
-
-(* TODO: - nested concats: <0>@(<0>@slice) -> <00> @ slice - s[0:1]@s[1:2] ->
-   s[0:2] *)
+  
 let rec fold_concat t =
   match t with
   | Concat (Bv Nil, t2) -> fold_concat t2
@@ -29,6 +27,12 @@ let rec fold_concat t =
       fold_concat (Concat (Slice (s1, ll, rr), t22))
     else
       Concat (t1, fold_concat (Concat (t21, t22)))
+  | Concat
+      (Concat ( t11, (Slice (s1, ll, lr) as t12)), (Slice (s2, rl, rr) as t2)) ->
+    if [%compare.equal: Sliceable.t] s1 s2 && lr = rl then
+      fold_concat (Concat (t11, Slice (s1, ll, rr)))
+    else
+      Concat (fold_concat (Concat (t11, t12)), t2)
   | Concat (t1, t2) -> Concat (fold_concat t1, fold_concat t2)
   | _ -> t