diff --git a/src/core/CCNativeint.ml b/src/core/CCNativeint.ml
new file mode 100644
index 00000000..b9692c38
--- /dev/null
+++ b/src/core/CCNativeint.ml
@@ -0,0 +1,51 @@
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+include Nativeint
+
+let equal (x:t) y = Pervasives.(=) x y
+
+module Infix = struct
+  let (+) = add
+
+  let (-) = sub
+
+  let (~-) = neg
+
+  let ( * ) = mul
+
+  let (/) = div
+
+  let (mod) = rem
+
+  let (land) = logand
+
+  let (lor) = logor
+
+  let (lxor) = logxor
+
+  let lnot = lognot
+
+  let (lsl) = shift_left
+
+  let (lsr) = shift_right_logical
+
+  let (asr) = shift_right
+
+  let (=) = equal
+
+  let (<>) = Pervasives.(<>)
+  let (<) = Pervasives.(<)
+  let (<=) = Pervasives.(<=)
+  let (>) = Pervasives.(>)
+  let (>=) = Pervasives.(>=)
+end
+include Infix
+
+let hash x = Pervasives.abs (to_int x)
+
+(** {2 Conversion} *)
+
+let of_string_exn = of_string
+
+let of_string x = try Some (of_string_exn x) with Failure _ -> None
+let of_string_opt = of_string
diff --git a/src/core/CCNativeint.mli b/src/core/CCNativeint.mli
new file mode 100644
index 00000000..e1e72f8d
--- /dev/null
+++ b/src/core/CCNativeint.mli
@@ -0,0 +1,148 @@
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+(** {1 Nativeint}
+
+    Helpers for processor-native integers.
+
+    This module provides operations on the type [nativeint] of signed 32-bit integers 
+    (on 32-bit platforms) or signed 64-bit integers (on 64-bit platforms). 
+    This integer type has exactly the same width as that of a pointer type in the C compiler. 
+    All arithmetic operations over nativeint are taken modulo 2{^32} or 2{^64} depending 
+    on the word size of the architecture.
+
+    Performance notice: values of type [nativeint] occupy more memory space than values of type [int], 
+    and arithmetic operations on [nativeint] are generally slower than those on [int]. 
+    Use [nativeint] only when the application requires the extra bit of precision over the [int] type.
+
+    @since NEXT_RELEASE *)
+
+include module type of struct include Nativeint end
+
+val ( + ) : t -> t -> t
+(** Addition. *)
+
+val ( - ) : t -> t -> t
+(** Subtraction. *)
+
+val ( ~- ) : t -> t
+(** Unary negation. *)
+
+val ( * ) : t -> t -> t
+(** Multiplication. *)
+
+val ( / ) : t -> t -> t
+(** Integer division.  Raise [Division_by_zero] if the second
+    argument is zero.  This division rounds the real quotient of
+    its arguments towards zero, as specified for {!Pervasives.(/)}. *)
+
+val ( mod ) : t -> t -> t
+(** [x mod y ] is the integer remainder.
+    If [y <> zero], the result of [x mod y] satisfies the following properties:
+    [zero <= x mod y < abs y] and
+    [x = ((x / y) * y) + (x mod y)].
+    If [y = 0], [x mod y] raises [Division_by_zero]. *)
+
+val ( land ) : t -> t -> t
+(** Bitwise logical and. *)
+
+val ( lor ) : t -> t -> t
+(** Bitwise logical or. *)
+
+val ( lxor ) : t -> t -> t
+(** Bitwise logical exclusive or. *)
+
+val lnot : t -> t
+(** Bitwise logical negation. *)
+
+val ( lsl ) : t -> int -> t
+(** [ x lsl y] shifts [x] to the left by [y] bits.
+    The result is unspecified if [y < 0] or [y >= bitsize], where [bitsize] is [32] on a 32-bit platform
+    and [64] on a 64-bit platform. *)
+
+val ( lsr ) : t -> int -> t
+(** [x lsr y] shifts [x] to the right by [y] bits.
+    This is a logical shift: zeroes are inserted in the vacated bits
+    regardless of the sign of [x].
+    The result is unspecified if [y < 0] or [y >= bitsize]. *)
+
+val ( asr ) : t -> int -> t
+(** [x asr y] shifts [x] to the right by [y] bits.
+    This is an arithmetic shift: the sign bit of [x] is replicated
+    and inserted in the vacated bits.
+    The result is unspecified if [y < 0] or [y >= bitsize]. *)
+
+module Infix : sig
+  val (+) : t -> t -> t
+  val (-) : t -> t -> t
+  val (~-) : t -> t
+  val ( * ) : t -> t -> t
+  val (/) : t -> t -> t
+  val (mod) : t -> t -> t
+  val (land) : t -> t -> t
+  val (lor) : t -> t -> t
+  val (lxor) : t -> t -> t
+  val lnot : t -> t
+  val (lsl) : t -> int -> t
+  val (lsr) : t -> int -> t
+  val (asr) : t -> int -> t
+  val (=) : t -> t -> bool
+  val (<>) : t -> t -> bool
+  val (>) : t -> t -> bool
+  val (>=) : t -> t -> bool
+  val (<=) : t -> t -> bool
+  val (<) : t -> t -> bool
+end
+
+val equal : t -> t -> bool
+(** The equal function for native integers.
+    Like {!Pervasives.(=) x y)}. *)
+
+val hash : t -> int
+(** Like {!Pervasives.abs (to_int x)}. *)
+
+(** {2 Conversion} *)
+
+val to_int : t -> int
+(** Convert the given native integer (type [nativeint]) to an
+    integer (type [int]). The high-order bit is lost
+    during the conversion. *)
+
+val of_int : int -> t
+(** Alias to {!Nativeint.of_int}.
+    Convert the given integer (type [int]) to a native integer (type [nativeint]). *)
+
+val to_float : t -> float
+(** Convert the given native integer to a floating-point number. *)
+
+val of_float : float -> t
+(** Alias to {!Nativeint.of_float}.
+    Convert the given floating-point number to a native integer,
+    discarding the fractional part (truncate towards 0).
+    The result of the conversion is undefined if, after truncation, the number
+    is outside the range \[{!CCNativeint.min_int}, {!CCNativeint.max_int}\]. *)
+
+val to_string : t -> string
+(** Return the string representation of its argument, in decimal. *)
+
+val of_string_exn : string -> t
+(** Alias to {!Nativeint.of_string}.
+    Convert the given string to a native integer.
+    The string is read in decimal (by default, or if the string
+    begins with [0u]) or in hexadecimal, octal or binary if the
+    string begins with [0x], [0o] or [0b] respectively.
+
+    The [0u] prefix reads the input as an unsigned integer in the range
+    [[0, 2*CCNativeint.max_int+1]]. If the input exceeds {!CCNativeint.max_int}
+    it is converted to the signed integer
+    [CCInt64.min_int + input - CCNativeint.max_int - 1].
+
+    Raise [Failure "Nativeint.of_string"] if the given string is not
+    a valid representation of an integer, or if the integer represented
+    exceeds the range of integers representable in type [nativeint]. *)
+
+val of_string : string -> t option
+(** Safe version of {!of_string_exn}.
+    Like {!of_string_exn}, but return [None] instead of raising. *)
+
+val of_string_opt : string -> t option
+(** Alias to {!of_string}. *)
diff --git a/src/core/containers.ml b/src/core/containers.ml
index 7a1a1574..15945033 100644
--- a/src/core/containers.ml
+++ b/src/core/containers.ml
@@ -27,12 +27,13 @@ module Hashtbl = struct
 end
 module Heap = CCHeap
 module Int = CCInt
-module Int32 = CCInt32  
+module Int32 = CCInt32
 module Int64 = CCInt64
 module IO = CCIO
 module List = CCList
 module ListLabels = CCListLabels
 module Map = CCMap
+module Nativeint = CCNativeint
 module Option = CCOpt
 module Ord = CCOrd
 module Pair = CCPair