diff --git a/src/libraries/utils/pretty_utils.ml b/src/libraries/utils/pretty_utils.ml
index bac42ea030c7f3038e164f9c0acd9d38512bbb30..df97d37c80c5d5380d58f9219fe448d4b127acc9 100644
--- a/src/libraries/utils/pretty_utils.ml
+++ b/src/libraries/utils/pretty_utils.ml
@@ -37,15 +37,6 @@ let to_string ?margin pp x =
   Format.pp_print_flush f () ;
   Buffer.contents b
 
-let rec pp_print_string_fill out s =
-  if String.contains s ' ' then begin
-    let i = String.index s ' ' in
-    let l = String.length s in
-    let s1 = String.sub s 0 i in
-    let s2 = String.sub s (i+1) (l - i - 1) in
-    Format.fprintf out "%s@ %a" s1 pp_print_string_fill s2
-  end else Format.pp_print_string out s
-
 type sformat = (unit,Format.formatter,unit) format
 type 'a formatter = Format.formatter -> 'a -> unit
 type ('a,'b) formatter2 = Format.formatter -> 'a -> 'b -> unit
diff --git a/src/libraries/utils/pretty_utils.mli b/src/libraries/utils/pretty_utils.mli
index 9082720f017197f68bd737b3e7d4c9786299c2ff..c169cbe4fd9b75ce7866e219d4f9885c59df0ecf 100644
--- a/src/libraries/utils/pretty_utils.mli
+++ b/src/libraries/utils/pretty_utils.mli
@@ -57,9 +57,6 @@ val to_string: ?margin:int -> (Format.formatter -> 'a -> unit) -> 'a -> string
 
 (** {2 separators} *)
 
-val pp_print_string_fill : Format.formatter -> string -> unit
-(** transforms every space in a string in breakable spaces.*)
-
 val escape_underscores : string -> string
 
 (* ********************************************************************** *)