diff --git a/platform.d b/platform.d
index c7e3762..59d2e55 100644
--- a/platform.d
+++ b/platform.d
@@ -281,10 +281,10 @@ Lock(TicketMut* mut)
 	while (ticket != volatileLoad(&mut.next_ticket)) {}
 }
 
-void
+u64
 Unlock(TicketMut* mut)
 {
-	atomicFetchAdd!(MemoryOrder.rel, u64)(mut.next_ticket, 1);
+	return atomicFetchAdd!(MemoryOrder.rel, u64)(mut.next_ticket, 1);
 }
 
 __gshared const DNode!(SysMessage) g_sys_message;