diff -uri btrfs-progs-v4.0.1.orig/ctree.c btrfs-progs-v4.0.1/ctree.c
--- btrfs-progs-v4.0.1.orig/ctree.c	2015-06-19 03:43:12.000000000 -0500
+++ btrfs-progs-v4.0.1/ctree.c	2015-06-19 03:43:49.000000000 -0500
@@ -2588,7 +2588,7 @@
 	int ret = 0;
 
 	nritems = btrfs_header_nritems(parent);
-	if (slot != nritems -1) {
+	if (slot < nritems -1) {
 		memmove_extent_buffer(parent,
 			      btrfs_node_key_ptr_offset(slot),
 			      btrfs_node_key_ptr_offset(slot + 1),