diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 9927cca..514efb2 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1021,7 +1021,7 @@
 {
 	radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
 			sizeof(struct radix_tree_node), 0,
-			SLAB_PANIC, radix_tree_node_ctor, NULL);
+			SLAB_PANIC, radix_tree_node_ctor);
 	radix_tree_init_maxindex();
 	hotcpu_notifier(radix_tree_callback, 0);
 }