diff --git a/core/CCArray.ml b/core/CCArray.ml
index b63f8671..7de43cfe 100644
--- a/core/CCArray.ml
+++ b/core/CCArray.ml
@@ -110,10 +110,10 @@ let rec _foldi f acc a i j =
 let _reverse_in_place a i j =
   if i=j then ()
   else
-    for k = i to j/2 do
+    for k = i to (j-1)/2 do
       let t = a.(k) in
-      a.(k) <- a.(j-k);
-      a.(j-k) <- t;
+      a.(k) <- a.(j-1-k);
+      a.(j-1-k) <- t;
     done
 
 let rec _equal eq a1 i1 j1 a2 i2 j2 =
@@ -350,6 +350,8 @@ module Sub = struct
     if i+len > Array.length arr then invalid_arg "Array.Sub.make";
     { arr; i; j=i+len; }
 
+  let of_slice (arr,i,len) = make arr i ~len
+
   let full arr = { arr; i=0; j=Array.length arr; }
 
   let underlying a = a.arr
diff --git a/core/CCArray.mli b/core/CCArray.mli
index 7f4bd8e8..a961bd38 100644
--- a/core/CCArray.mli
+++ b/core/CCArray.mli
@@ -145,6 +145,11 @@ module Sub : sig
   (** Create a slice.
       @raise Invalid_argument if the slice isn't valid *)
 
+  val of_slice : ('a array * int * int) -> 'a t
+  (** Make a sub-array from a triple [(arr, i, len)] where [arr] is the array,
+      [i] the offset in [arr], and [len] the number of elements of the slice.
+      @raise Invalid_argument if the slice isn't valid (See {!make}) *)
+
   val full : 'a array -> 'a t
   (** Slice that covers the full array *)