diff --git a/lib/opcodes.py b/lib/opcodes.py
index 93ea6ed11101fdf8d6b5b7e5a600b281c0399985..46f6a0ae6c9287d331231b6a72c55529979757cf 100644
--- a/lib/opcodes.py
+++ b/lib/opcodes.py
@@ -53,7 +53,8 @@ class OpInitCluster(OpCode):
   """Initialise the cluster."""
   OP_ID = "OP_CLUSTER_INIT"
   __slots__ = ["cluster_name", "secondary_ip", "hypervisor_type",
-               "vg_name", "mac_prefix", "def_bridge", "master_netdev"]
+               "vg_name", "mac_prefix", "def_bridge", "master_netdev",
+               "file_storage_dir"]
 
 
 class OpDestroyCluster(OpCode):