diff --git a/dune-project b/dune-project
index 3ed2c1b..3e8fcbf 100644
--- a/dune-project
+++ b/dune-project
@@ -27,6 +27,7 @@
   dune)
  (depopts
   hmap
+  unix
   (mtime
    (>= 2.0)))
  (tags
diff --git a/trace.opam b/trace.opam
index 446cdb4..83bc324 100644
--- a/trace.opam
+++ b/trace.opam
@@ -16,6 +16,7 @@ depends: [
 ]
 depopts: [
   "hmap"
+  "unix"
   "mtime" {>= "2.0"}
 ]
 build: [