diff --git a/dune-project b/dune-project
index 32d47f5..3dfa25b 100644
--- a/dune-project
+++ b/dune-project
@@ -29,6 +29,7 @@
    (trace (= :version))
    (mtime (>= 2.0))
    base-unix
+   atomic
    dune)
  (tags
   (trace tracing catapult)))
diff --git a/trace-tef.opam b/trace-tef.opam
index b7d427c..2a4fd6f 100644
--- a/trace-tef.opam
+++ b/trace-tef.opam
@@ -14,6 +14,7 @@ depends: [
   "trace" {= version}
   "mtime" {>= "2.0"}
   "base-unix"
+  "atomic"
   "dune" {>= "2.9"}
   "odoc" {with-doc}
 ]