diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index bc03ecc4dfd2..e5cab5c4e383 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -2172,7 +2172,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
 			offset = radix_tree_find_next_bit(node, IDR_FREE,
 							offset + 1);
 			start = next_index(start, node, offset);
-			if (start > max)
+			if (start > max || start == 0)
 				return ERR_PTR(-ENOSPC);
 			while (offset == RADIX_TREE_MAP_SIZE) {
 				offset = node->offset + 1;