wireshark: use correct subtree
diff --git a/wireshark_gen/templates/_ofclass_dissector.lua b/wireshark_gen/templates/_ofclass_dissector.lua
index d4bee01..4651e93 100644
--- a/wireshark_gen/templates/_ofclass_dissector.lua
+++ b/wireshark_gen/templates/_ofclass_dissector.lua
@@ -1,5 +1,5 @@
 :: from loxi_ir import *
-function ${name}(buf, root)
+function ${name}(buf, subtree)
 :: for m in ofclass.members:
 :: if isinstance(m, OFTypeMember):
     -- type ${m.name}
diff --git a/wireshark_gen/templates/openflow.lua b/wireshark_gen/templates/openflow.lua
index 098557b..e1b9319 100644
--- a/wireshark_gen/templates/openflow.lua
+++ b/wireshark_gen/templates/openflow.lua
@@ -66,7 +66,7 @@
     local version_val = buf(0,1):uint()
     local type_val = buf(1,1):uint()
     if of_message_dissectors[version_val] and of_message_dissectors[version_val][type_val] then
-        of_message_dissectors[version_val][type_val](buf, root)
+        of_message_dissectors[version_val][type_val](buf, subtree)
     end
 end