diff --git a/packages/effect/test/Mailbox.test.ts b/packages/effect/test/Mailbox.test.ts
index 5fc9606bf5..4be31dc170 100644
--- a/packages/effect/test/Mailbox.test.ts
+++ b/packages/effect/test/Mailbox.test.ts
@@ -1,4 +1,4 @@
-import { Effect, Exit, Fiber, Mailbox } from "effect"
+import { Chunk, Effect, Exit, Fiber, Mailbox, Stream } from "effect"
 import { assert, describe, it } from "effect/test/utils/extend"
 
 describe("Mailbox", () => {
@@ -70,4 +70,15 @@ describe("Mailbox", () => {
       yield* mailbox.done(Exit.void)
       assert.deepStrictEqual(yield* fiber.await, Exit.succeed([[] as Array<number>, true] as const))
     }))
+
+  it.effect("offer ordering", () =>
+    Effect.gen(function*() {
+      const mailbox = yield* Mailbox.make<number>(2)
+      yield* Effect.fork(mailbox.offerAll([1, 2, 3, 4]))
+      yield* Effect.fork(mailbox.offerAll([5, 6, 7, 8]))
+      yield* Effect.fork(mailbox.offer(9))
+      yield* Effect.fork(mailbox.end)
+      const items = yield* Stream.runCollect(Mailbox.toStream(mailbox))
+      assert.deepStrictEqual(Chunk.toReadonlyArray(items), [1, 2, 3, 4, 5, 6, 7, 8, 9])
+    }))
 })