diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
index 122f02f9941b..31dd4ccd3baa 100644
--- a/lib/rbtree_test.c
+++ b/lib/rbtree_test.c
@@ -114,6 +114,16 @@ static int black_path_count(struct rb_node *rb)
 	return count;
 }
 
+static void check_postorder(int nr_nodes)
+{
+	struct rb_node *rb;
+	int count = 0;
+	for (rb = rb_first_postorder(&root); rb; rb = rb_next_postorder(rb))
+		count++;
+
+	WARN_ON_ONCE(count != nr_nodes);
+}
+
 static void check(int nr_nodes)
 {
 	struct rb_node *rb;
@@ -136,6 +146,8 @@ static void check(int nr_nodes)
 
 	WARN_ON_ONCE(count != nr_nodes);
 	WARN_ON_ONCE(count < (1 << black_path_count(rb_last(&root))) - 1);
+
+	check_postorder(nr_nodes);
 }
 
 static void check_augmented(int nr_nodes)