diff --git a/sledge/nonstdlib/NS.ml b/sledge/nonstdlib/NS.ml
index 6af127af3..078f4afb6 100644
--- a/sledge/nonstdlib/NS.ml
+++ b/sledge/nonstdlib/NS.ml
@@ -82,6 +82,13 @@ module List = List
 module Array = struct
   include Core.Array
 
+  let hash_fold_t hash_fold_elt s a =
+    Hash.Builtin.hash_fold_array_frozen hash_fold_elt s a
+
+  module Import = struct
+    type 'a array = 'a t [@@deriving compare, equal, hash, sexp]
+  end
+
   let pp sep pp_elt fs a = List.pp sep pp_elt fs (to_list a)
 
   let fold_map_inplace a ~init ~f =
@@ -95,6 +102,7 @@ module Array = struct
     !s
 end
 
+include Array.Import
 module IArray = IArray
 include IArray.Import
 module Set = Set
diff --git a/sledge/nonstdlib/NS.mli b/sledge/nonstdlib/NS.mli
index 28c9cbcfa..58af30089 100644
--- a/sledge/nonstdlib/NS.mli
+++ b/sledge/nonstdlib/NS.mli
@@ -79,12 +79,19 @@ module List = List
 module Array : sig
   include module type of Array
 
+  type 'a t = 'a Array.t [@@deriving compare, equal, hash, sexp]
+
+  module Import : sig
+    type 'a array = 'a t [@@deriving compare, equal, hash, sexp]
+  end
+
   val pp : (unit, unit) fmt -> 'a pp -> 'a array pp
 
   val fold_map_inplace :
     'a array -> init:'s -> f:('s -> 'a -> 's * 'a) -> 's
 end
 
+include module type of Array.Import
 module IArray = IArray
 include module type of IArray.Import
 module Set = Set