diff --git a/src/libraries/utils/markdown.ml b/src/libraries/utils/markdown.ml
index e31749a3b98a3ca9270d21494899af56ae9c0e27..0295d8007b6588eac586be4811bc619ef65947d2 100644
--- a/src/libraries/utils/markdown.ml
+++ b/src/libraries/utils/markdown.ml
@@ -121,7 +121,7 @@ type href = [
   | `Section of string * string
 ]
 
-let filepath m = Transitioning.String.split_on_char '/' m
+let filepath m = String.split_on_char '/' m
 
 let rec relative source target =
   match source , target with
@@ -134,7 +134,7 @@ let lnk target =
 
 let id m =
   let buffer = Buffer.create (String.length m) in
-  let lowercase = Transitioning.Char.lowercase_ascii in
+  let lowercase = Char.lowercase_ascii in
   let dash = ref false in
   let emit c =
     if !dash then (Buffer.add_char buffer '-' ; dash := false) ;
@@ -220,7 +220,7 @@ let code ?(lang="") pp fmt =
     let bfmt = Format.formatter_of_buffer buffer in
     pp bfmt ; Format.pp_print_flush bfmt () ;
     let content = Buffer.contents buffer in
-    let lines = Transitioning.String.split_on_char '\n' content in
+    let lines = String.split_on_char '\n' content in
     let rec clean = function [] -> [] | ""::w -> clean w | w -> w in
     List.iter
       (fun l -> Format.fprintf fmt "@\n%s" l)
diff --git a/src/plugins/server/doc.ml b/src/plugins/server/doc.ml
index b7e928736d3a3c5653dce564ece5bcd23dbe8be9..0d141b3f018ecdd7b1946c5fa5f0db5a76bfd16f 100644
--- a/src/plugins/server/doc.ml
+++ b/src/plugins/server/doc.ml
@@ -97,7 +97,7 @@ let _ = page `Protocol ~title:"Architecture" ~filename:"server.md"
 let title_of_chapter = function
   | `Protocol -> "Server Protocols"
   | `Kernel -> "Kernel Services"
-  | `Plugin name -> "Plugin " ^ Transitioning.String.capitalize_ascii name
+  | `Plugin name -> "Plugin " ^ String.capitalize_ascii name
 
 let pages_of_chapter c =
   let w = ref [] in
diff --git a/src/plugins/server/request.ml b/src/plugins/server/request.ml
index 7157ce172c61d051239134d8ffc6718d77fd3fc4..b355b3907879b1e91eef4345b217d39680fb98bc 100644
--- a/src/plugins/server/request.ml
+++ b/src/plugins/server/request.ml
@@ -51,8 +51,6 @@ type 'a output = (module Output with type t = 'a)
 (* --- Sanity Checks                                                      --- *)
 (* -------------------------------------------------------------------------- *)
 
-module STR = Transitioning.String
-
 let re_set = Str.regexp_string_case_fold "SET"
 let re_get = Str.regexp_case_fold "\\(GET\\|PRINT\\)"
 let re_exec = Str.regexp_case_fold "\\(EXEC\\|COMPUTE\\)"
@@ -67,8 +65,8 @@ let check_name name =
       "Request %S is not a dot-separated list of (camlCased) identifiers" name
 
 let check_plugin plugin name =
-  let p = STR.lowercase_ascii plugin in
-  let n = STR.lowercase_ascii name in
+  let p = String.lowercase_ascii plugin in
+  let n = String.lowercase_ascii name in
   let k = String.length plugin in
   if not (String.length name > k &&
           String.sub n 0 k = p &&
@@ -76,7 +74,7 @@ let check_plugin plugin name =
   then
     Senv.warning ~wkey:wpage
       "Request '%s' shall be named « %s.* »"
-      name (STR.capitalize_ascii plugin)
+      name (String.capitalize_ascii plugin)
 
 let check_page page name =
   match Doc.chapter page with
diff --git a/src/plugins/server/syntax.ml b/src/plugins/server/syntax.ml
index a4777168f6e71793a90a46648c66bbcd30c1b6b4..565a227cde54a50190a518e5d45f036b9b44d913 100644
--- a/src/plugins/server/syntax.ml
+++ b/src/plugins/server/syntax.ml
@@ -22,12 +22,11 @@
 
 (* -------------------------------------------------------------------------- *)
 
-module STR = Transitioning.String
 module Senv = Server_parameters
 
 let check_plugin plugin name =
-  let p = STR.lowercase_ascii plugin in
-  let n = STR.lowercase_ascii name in
+  let p = String.lowercase_ascii plugin in
+  let n = String.lowercase_ascii name in
   let k = String.length plugin in
   if not (String.length name > k &&
           String.sub n 0 k = p &&