diff --git a/dune-project b/dune-project
index 4675388..8526f38 100644
--- a/dune-project
+++ b/dune-project
@@ -62,7 +62,7 @@
    (>= 4.12))
   dune
   base-unix
-  iomux
+  (iomux (>= 0.3))
   (nanoev
    (= :version))
   (nanoev-picos
diff --git a/nanoev-posix.opam b/nanoev-posix.opam
index d5280ad..6f2f9fc 100644
--- a/nanoev-posix.opam
+++ b/nanoev-posix.opam
@@ -11,7 +11,7 @@ depends: [
   "ocaml" {>= "4.12"}
   "dune" {>= "2.7"}
   "base-unix"
-  "iomux"
+  "iomux" {>= "0.3"}
   "nanoev" {= version}
   "nanoev-picos" {= version}
   "mtime" {>= "2.0"}