diff --git a/src/core/CCNativeint.ml b/src/core/CCNativeint.ml
index 065e74fa..66dfa0e7 100644
--- a/src/core/CCNativeint.ml
+++ b/src/core/CCNativeint.ml
@@ -2,8 +2,13 @@
 
 include Nativeint
 
+[@@@iflt 4.13]
+
 let min : t -> t -> t = Stdlib.min
 let max : t -> t -> t = Stdlib.max
+
+[@@@endif]
+
 let hash x = Stdlib.abs (to_int x)
 let sign i = compare i zero
 
@@ -95,8 +100,7 @@ let random_range i j st = add i (random (sub j i) st)
 (** {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
+let of_string = of_string_opt
 let most_significant_bit = logxor (neg 1n) (shift_right_logical (neg 1n) 1)
 
 type output = char -> unit
diff --git a/src/core/CCNativeint.mli b/src/core/CCNativeint.mli
index 011e128f..16f3a74b 100644
--- a/src/core/CCNativeint.mli
+++ b/src/core/CCNativeint.mli
@@ -2,14 +2,14 @@
 
 (** 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 
+    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]. 
+    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 2.1 *)
@@ -117,7 +117,7 @@ val pp_binary : t printer
 
 module Infix : sig
   val ( + ) : t -> t -> t
-  (** [x + y] is the sum of [x] and [y]. 
+  (** [x + y] is the sum of [x] and [y].
       Addition. *)
 
   val ( - ) : t -> t -> t