diff --git a/CHANGES.md b/CHANGES.md
index 71b5c96d59..81048ff039 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -3,6 +3,9 @@
 * Lwt, Mirage: Add log warnings for uncaught exceptions (#592 by @ansiwen)
 * Port opam files to opam2 and add local synopsis and descriptions.
 * Lwt: Add Expert response action for servers (#647 by @andreas)
+* Use the namespaced `js_of_ocaml` interfaces from 3.3.0 onwards (#654 @avsm)
+* Use Base64 3.1.0 interfaces (#655 @avsm)
+* Clean up redundant conflicts in the `opam` files (@avsm)
 
 Compatibility breaking interface changes:
 
diff --git a/cohttp-lwt-unix.opam b/cohttp-lwt-unix.opam
index df4c5856bc..8bf4c5bad9 100644
--- a/cohttp-lwt-unix.opam
+++ b/cohttp-lwt-unix.opam
@@ -37,9 +37,6 @@ depends: [
   "base-unix"
   "ounit" {with-test}
 ]
-conflicts: [
-  "lwt" {< "2.5.0"}
-]
 build: [
   ["dune" "subst"] {pinned}
   ["dune" "build" "-p" name "-j" jobs]
diff --git a/cohttp-lwt.opam b/cohttp-lwt.opam
index 2ed1f3347c..f0565a4afb 100644
--- a/cohttp-lwt.opam
+++ b/cohttp-lwt.opam
@@ -28,14 +28,11 @@ depends: [
   "ocaml" {>= "4.04.1"}
   "dune" {build & >= "1.1.0"}
   "cohttp" {>= "1.0.0"}
-  "lwt"
+  "lwt" {>= "2.5.0"}
   "sexplib0"
   "ppx_sexp_conv" {>= "v0.9.0"}
   "logs"
 ]
-conflicts: [
-  "lwt" {< "2.5.0"}
-]
 build: [
   ["dune" "subst"] {pinned}
   ["dune" "build" "-p" name "-j" jobs]
diff --git a/cohttp.opam b/cohttp.opam
index 31f77cf669..85d3c7d8bd 100644
--- a/cohttp.opam
+++ b/cohttp.opam
@@ -41,7 +41,7 @@ depends: [
   "ppx_fields_conv" {>= "v0.9.0"}
   "ppx_sexp_conv" {>= "v0.9.0"}
   "stringext"
-  "base64" {>= "2.0.0" & <"3.0.0"}
+  "base64" {>= "3.1.0"}
   "fmt" {with-test}
   "jsonm" {build}
   "alcotest" {with-test}
diff --git a/cohttp/src/auth.ml b/cohttp/src/auth.ml
index 1b22daf3ac..a153561627 100644
--- a/cohttp/src/auth.ml
+++ b/cohttp/src/auth.ml
@@ -29,13 +29,13 @@ type credential = [
 let string_of_credential (cred:credential) =
   match cred with
   | `Basic (user, pass) ->
-    "Basic " ^ (B64.encode (sprintf "%s:%s" user pass))
+    "Basic " ^ (Base64.encode_string (sprintf "%s:%s" user pass))
   | `Other buf -> buf
 
 let credential_of_string (buf:string) : credential =
   try
     let b64 = Scanf.sscanf buf "Basic %s" (fun b -> b) in
-    match Stringext.split ~on:':' (B64.decode b64) ~max:2 with
+    match Stringext.split ~on:':' (Base64.decode_exn b64) ~max:2 with
     |[user;pass] -> `Basic (user,pass)
     |_ -> `Other buf
   with _ -> `Other buf