diff --git a/tests/kernel/mbox/mbox_api/prj.conf b/tests/kernel/mbox/mbox_api/prj.conf
index 284f3e753a9..237b71779ea 100644
--- a/tests/kernel/mbox/mbox_api/prj.conf
+++ b/tests/kernel/mbox/mbox_api/prj.conf
@@ -1,2 +1,3 @@
 CONFIG_ZTEST=y
-CONFIG_NUM_MBOX_ASYNC_MSGS=2
+CONFIG_NUM_MBOX_ASYNC_MSGS=5
+CONFIG_OBJECT_TRACING=y