diff --git a/src/FindFiles.ml b/src/FindFiles.ml
index abf949cc..ce0021db 100644
--- a/src/FindFiles.ml
+++ b/src/FindFiles.ml
@@ -46,11 +46,11 @@ let isSourceFile name =
   || Filename.check_suffix name ".mli"
 
 let compiledNameSpace name =
-  Str.split (Str.regexp_string "-") name
+  String.split_on_char '-' name
   |> List.map String.capitalize_ascii
   |> String.concat ""
   (* Remove underscores??? Whyyy bucklescript, whyyyy *)
-  |> Str.split (Str.regexp_string "_")
+  |> String.split_on_char '_'
   |> String.concat ""
 
 let compiledBaseName ~namespace name =
diff --git a/src/Packages.ml b/src/Packages.ml
index b7754704..d772400f 100644
--- a/src/Packages.ml
+++ b/src/Packages.ml
@@ -79,7 +79,7 @@ let newBsPackage rootPath =
                    match item |> Json.string with
                    | None -> opens
                    | Some s -> (
-                     let parts = Utils.split_on_char ' ' s in
+                     let parts = String.split_on_char ' ' s in
                      match parts with
                      | "-open" :: name :: _ -> name :: opens
                      | _ -> opens))
diff --git a/src/Utils.ml b/src/Utils.ml
index 819073ce..444b4f5c 100644
--- a/src/Utils.ml
+++ b/src/Utils.ml
@@ -1,18 +1,3 @@
-(*
-  steal from OCaml stdlib
-  https://github.com/ocaml/ocaml/blob/7c9c210884e1b46f21af5bb4dfab995bb3336cf7/stdlib/string.ml#L205-L214
-*)
-let split_on_char sep s =
-  let open String in
-  let r = ref [] in
-  let j = ref (length s) in
-  for i = length s - 1 downto 0 do
-    if unsafe_get s i = sep then (
-      r := sub s (i + 1) (!j - i - 1) :: !r;
-      j := i)
-  done;
-  sub s 0 !j :: !r
-
 let topLoc fname =
   {
     Location.loc_start =