diff --git a/tests/bsim/bluetooth/audio/src/mcc_test.c b/tests/bsim/bluetooth/audio/src/mcc_test.c
index bd5ffeaf41b..352be746ddf 100644
--- a/tests/bsim/bluetooth/audio/src/mcc_test.c
+++ b/tests/bsim/bluetooth/audio/src/mcc_test.c
@@ -1506,6 +1506,14 @@ static void test_read_icon_obj_id(void)
 {
 	int err;
 
+	/* Invalid behavior */
+	err = bt_mcc_read_icon_obj_id(NULL);
+	if (err == 0) {
+		FAIL("bt_mcc_read_icon_obj_id did not fail with NULL conn");
+		return;
+	}
+
+	/* Valid behavior */
 	UNSET_FLAG(icon_object_id_read);
 
 	err = bt_mcc_read_icon_obj_id(default_conn);