diff --git a/CHANGES.md b/CHANGES.md
index 3fa583c..77a4dd0 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,4 +1,9 @@
 
+# 0.5
+
+- perf: reduce overhead in trace-tef
+- perf: add Mpsc_queue, adapted from picos, to trace-tef
+
 # 0.4
 
 - add `?data` to `counter_int` and `counter_float`
diff --git a/dune-project b/dune-project
index 3dfa25b..e69091a 100644
--- a/dune-project
+++ b/dune-project
@@ -2,7 +2,7 @@
 
 (name trace)
 (generate_opam_files true)
-(version 0.4)
+(version 0.5)
 
 (source
  (github c-cube/ocaml-trace))
diff --git a/trace-tef.opam b/trace-tef.opam
index 2a4fd6f..464cee8 100644
--- a/trace-tef.opam
+++ b/trace-tef.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:
   "A simple backend for trace, emitting Catapult/TEF JSON into a file"
 maintainer: ["Simon Cruanes"]
diff --git a/trace.opam b/trace.opam
index b2d9513..c68d219 100644
--- a/trace.opam
+++ b/trace.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:
   "A stub for tracing/observability, agnostic in how data is collected"
 maintainer: ["Simon Cruanes"]