diff --git a/opam b/opam
index 4f1f6c51b5..6d67ffbf89 100644
--- a/opam
+++ b/opam
@@ -31,7 +31,7 @@ depends: [
   "lwt_log"
   "lwt_ppx" {>= "1.2.3"}
   "tyxml" {>= "4.4.0" & < "5.0.0"}
-  "ocsigenserver" {>= "5.0.0" & < "6.0.0"}
+  "ocsigenserver" {>= "5.1.0" & < "6.0.0"}
   "ipaddr" {>= "2.1"}
   "reactiveData" {>= "0.2.1"}
   "base-bytes"
diff --git a/src/lib/eliom_content_core.server.ml b/src/lib/eliom_content_core.server.ml
index 3c722a23e7..7cb3a861c1 100644
--- a/src/lib/eliom_content_core.server.ml
+++ b/src/lib/eliom_content_core.server.ml
@@ -155,7 +155,7 @@ module Xml = struct
     let empty_name = "" in
     empty_name, RAClient (crypto, init, Eliom_lib.to_poly x)
 
-  let closing_cdata = Pcre.(regexp (quote "]]>"))
+  let closing_cdata = Re.Pcre.(regexp (quote "]]>"))
 
   let cdata s =
     (* GK *)
@@ -164,7 +164,7 @@ module Xml = struct
      *)
     let s' =
       "\n<![CDATA[\n"
-      ^ Pcre.replace ~rex:closing_cdata ~itempl:(Pcre.subst "") s
+      ^ Re.replace_string closing_cdata ~by:"" s
       ^ "\n]]>\n"
     in
     encodedpcdata s'
@@ -176,7 +176,7 @@ module Xml = struct
      *)
     let s' =
       "\n//<![CDATA[\n"
-      ^ Pcre.replace ~rex:closing_cdata ~itempl:(Pcre.subst "") s
+      ^ Re.replace_string closing_cdata ~by:"" s
       ^ "\n//]]>\n"
     in
     encodedpcdata s'
@@ -188,7 +188,7 @@ module Xml = struct
      *)
     let s' =
       "\n/* <![CDATA[ */\n"
-      ^ Pcre.replace ~rex:closing_cdata ~itempl:(Pcre.subst "") s
+      ^ Re.replace_string closing_cdata ~by:"" s
       ^ "\n/* ]]> */\n"
     in
     encodedpcdata s'
diff --git a/src/lib/eliom_parameter.server.ml b/src/lib/eliom_parameter.server.ml
index ca923e9630..bcbdbe506d 100644
--- a/src/lib/eliom_parameter.server.ml
+++ b/src/lib/eliom_parameter.server.ml
@@ -47,15 +47,15 @@ let all_suffix_user ?client_to_and_of ~(of_string : string -> 'a)
 let regexp reg dest ~to_string n =
   user_type
     (fun s ->
-      match Pcre.exec ~rex:reg ~flags:[`ANCHORED] ~pos:0 s with
-      | _ -> (
+      match Re.Pcre.exec ~rex:reg ~pos:0 s with
+      | g when Re.Group.start g 0 = 0 -> (
         try
           Ocsigen_extensions.replace_user_dir reg
             (Ocsigen_extensions.parse_user_dir dest)
             s
         with Ocsigen_extensions.NoSuchUser ->
           raise (Failure "User does not exist"))
-      | exception Not_found -> raise (Failure "Regexp not matching"))
+      | _ | exception Not_found -> raise (Failure "Regexp not matching"))
     to_string n
 
 let all_suffix_regexp reg dest ~(to_string : 'a -> string) (n : string)
@@ -63,15 +63,15 @@ let all_suffix_regexp reg dest ~(to_string : 'a -> string) (n : string)
   =
   all_suffix_user
     (fun s ->
-      match Pcre.exec ~rex:reg ~flags:[`ANCHORED] ~pos:0 s with
-      | _ -> (
+      match Re.Pcre.exec ~rex:reg ~pos:0 s with
+      | g when Re.Group.start g 0 = 0 -> (
         try
           Ocsigen_extensions.replace_user_dir reg
             (Ocsigen_extensions.parse_user_dir dest)
             s
         with Ocsigen_extensions.NoSuchUser ->
           raise (Failure "User does not exist"))
-      | exception Not_found -> raise (Failure "Regexp not matching"))
+      | _ | exception Not_found -> raise (Failure "Regexp not matching"))
     to_string n
 
 (* Non localized parameters *)
diff --git a/src/lib/eliom_parameter.server.mli b/src/lib/eliom_parameter.server.mli
index 4dbf0b4b9f..d632bae4ac 100644
--- a/src/lib/eliom_parameter.server.mli
+++ b/src/lib/eliom_parameter.server.mli
@@ -60,7 +60,7 @@ val type_checker
     instead of the service handler. *)
 
 val regexp
-  :  Pcre.regexp
+  :  Re.Pcre.regexp
   -> string
   -> to_string:(string -> string)
   -> string
@@ -69,12 +69,12 @@ val regexp
     the regular expression [r] as parameter, labeled [s], and that will
     be rewritten in d.  The syntax of regexp is PCRE's one (uses then
     [Pcre] bindings).  For example: [regexp
-    (Pcre.regexp "\\[(.* )\\]") "($1)" "myparam"] will match
+    (Re.Pcre.regexp "\\[(.* )\\]") "($1)" "myparam"] will match
     the parameter [myparam=[hello]] and send the string ["(hello)"] to
     the service handler.  *)
 
 val all_suffix_regexp
-  :  Pcre.regexp
+  :  Re.Pcre.regexp
   -> string
   -> to_string:(string -> string)
   -> string