diff --git a/CHANGES.md b/CHANGES.md
index e67559df..ba3b1b03 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,4 +1,10 @@
 
+## 0.5
+
+- new implementation for ocurl backend, using ezcurl and queues
+- refactor lwt: Use `try%lwt` over `Lwt.catch`
+- add `opentelemetry.trace` (optional, depends on `trace`)
+
 ## 0.4
 
 - expose `Scope.get_surrounding`
diff --git a/dune-project b/dune-project
index 05196efd..6e948d02 100644
--- a/dune-project
+++ b/dune-project
@@ -4,7 +4,7 @@
 (source
  (github imandra-ai/ocaml-opentelemetry))
 
-(version 0.4)
+(version 0.5)
 
 (authors "the Imandra team and contributors")
 (maintainers "the Imandra team and contributors")
@@ -33,7 +33,7 @@
    (cohttp-lwt-unix :with-test)
    (odoc :with-doc)
    (lwt (>= "5.3"))
-   lwt_ppx)
+   (lwt_ppx (>= "2.0")))
  (tags
   (instrumentation tracing opentelemetry datadog lwt)))
 
@@ -70,7 +70,7 @@
    (pbrt (>= 2.2))
    (odoc :with-doc)
    (lwt (>= "5.3"))
-   lwt_ppx
+   (lwt_ppx (>= "2.0"))
    cohttp-lwt
    cohttp-lwt-unix)
   (synopsis "Collector client for opentelemetry, using cohttp + lwt"))
diff --git a/opentelemetry-client-cohttp-lwt.opam b/opentelemetry-client-cohttp-lwt.opam
index 9ef83e7c..91752b3f 100644
--- a/opentelemetry-client-cohttp-lwt.opam
+++ b/opentelemetry-client-cohttp-lwt.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.4"
+version: "0.5"
 synopsis: "Collector client for opentelemetry, using cohttp + lwt"
 maintainer: ["the Imandra team and contributors"]
 authors: ["the Imandra team and contributors"]
@@ -15,7 +15,7 @@ depends: [
   "pbrt" {>= "2.2"}
   "odoc" {with-doc}
   "lwt" {>= "5.3"}
-  "lwt_ppx"
+  "lwt_ppx" {>= "2.0"}
   "cohttp-lwt"
   "cohttp-lwt-unix"
 ]
diff --git a/opentelemetry-client-ocurl.opam b/opentelemetry-client-ocurl.opam
index 1f1b4c4d..e88b8a2a 100644
--- a/opentelemetry-client-ocurl.opam
+++ b/opentelemetry-client-ocurl.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.4"
+version: "0.5"
 synopsis: "Collector client for opentelemetry, using http + ezcurl"
 maintainer: ["the Imandra team and contributors"]
 authors: ["the Imandra team and contributors"]
diff --git a/opentelemetry-cohttp-lwt.opam b/opentelemetry-cohttp-lwt.opam
index ba99a399..77221b9a 100644
--- a/opentelemetry-cohttp-lwt.opam
+++ b/opentelemetry-cohttp-lwt.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.4"
+version: "0.5"
 synopsis: "Opentelemetry tracing for Cohttp HTTP servers"
 maintainer: ["the Imandra team and contributors"]
 authors: ["the Imandra team and contributors"]
diff --git a/opentelemetry-lwt.opam b/opentelemetry-lwt.opam
index f739e701..9740df2a 100644
--- a/opentelemetry-lwt.opam
+++ b/opentelemetry-lwt.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.4"
+version: "0.5"
 synopsis: "Lwt-compatible instrumentation for https://opentelemetry.io"
 maintainer: ["the Imandra team and contributors"]
 authors: ["the Imandra team and contributors"]
@@ -15,7 +15,7 @@ depends: [
   "cohttp-lwt-unix" {with-test}
   "odoc" {with-doc}
   "lwt" {>= "5.3"}
-  "lwt_ppx"
+  "lwt_ppx" {>= "2.0"}
 ]
 build: [
   ["dune" "subst"] {dev}
diff --git a/opentelemetry.opam b/opentelemetry.opam
index f320f643..d7cd5e08 100644
--- a/opentelemetry.opam
+++ b/opentelemetry.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.4"
+version: "0.5"
 synopsis: "Instrumentation for https://opentelemetry.io"
 maintainer: ["the Imandra team and contributors"]
 authors: ["the Imandra team and contributors"]