diff --git a/dune-project b/dune-project
index 666b394f..050eb9d8 100644
--- a/dune-project
+++ b/dune-project
@@ -36,6 +36,7 @@
 (package
   (name moonpool-lwt)
   (synopsis "Event loop for moonpool based on Lwt-engine")
+  (allow_empty)  ; on < 5.0
   (depends
     (moonpool (= :version))
     (ocaml (>= 5.0))
diff --git a/src/core/suspend_.ml b/src/core/suspend_.ml
index cdd680a5..68ae01bb 100644
--- a/src/core/suspend_.ml
+++ b/src/core/suspend_.ml
@@ -16,6 +16,8 @@ type suspension_handler = {
 
 [@@@ocaml.alert "-unstable"]
 
+module A = Atomic_
+
 type _ Effect.t +=
   | Suspend : suspension_handler -> unit Effect.t
   | Yield : unit Effect.t