diff --git a/otherlibs/num/int_misc.ml b/otherlibs/num/int_misc.ml
index 15b3a279e..5e8a8170f 100644
--- a/otherlibs/num/int_misc.ml
+++ b/otherlibs/num/int_misc.ml
@@ -24,7 +24,7 @@ let num_bits_int n = num_bits_int_aux (abs n);;
 
 let sign_int i = if i = 0 then 0 else if i > 0 then 1 else -1;;
 
-let length_of_int = (Sys.get_config()).Sys.word_size - 2;;
+let length_of_int = Sys.word_size - 2;;
 
 let monster_int = 1 lsl length_of_int;;
 let biggest_int = monster_int - 1;;
diff --git a/otherlibs/num/nat.ml b/otherlibs/num/nat.ml
index 43e6a03d8..377fccae9 100644
--- a/otherlibs/num/nat.ml
+++ b/otherlibs/num/nat.ml
@@ -44,7 +44,7 @@ external land_digit_nat: nat -> int -> nat -> int -> unit = "land_digit_nat"
 external lor_digit_nat: nat -> int -> nat -> int -> unit = "lor_digit_nat"
 external lxor_digit_nat: nat -> int -> nat -> int -> unit = "lxor_digit_nat"
 
-let length_of_digit = (Sys.get_config ()).Sys.word_size;;
+let length_of_digit = Sys.word_size;;
 
 let make_nat len =
   if len < 0 then invalid_arg "make_nat" else