diff --git a/session-cohttp-lwt.opam b/session-cohttp-lwt.opam
index ec48a6d..435cab6 100644
--- a/session-cohttp-lwt.opam
+++ b/session-cohttp-lwt.opam
@@ -11,6 +11,7 @@ depends: [
   "dune" {>= "1.0"}
   "session-cohttp" {= version}
   "cohttp-lwt"
+  "cohttp-lwt-unix" { with-test }
   "lwt"
 ]
 build: [