diff --git a/src/python/loxi/of12/common.py b/src/python/loxi/of12/common.py
index 4bb1449..b091544 100644
--- a/src/python/loxi/of12/common.py
+++ b/src/python/loxi/of12/common.py
@@ -115,7 +115,7 @@
         obj.type = reader.read("!H")[0]
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         return obj
 
     def __eq__(self, other):
@@ -214,7 +214,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.flags = reader.read("!L")[0]
         obj.port_no = util.unpack_port_no(reader)
         obj.loopback_port_no = util.unpack_port_no(reader)
@@ -342,7 +342,7 @@
         assert(_type == 0)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.port_no = reader.read("!L")[0]
         obj.ingress_tpid = reader.read("!H")[0]
         obj.ingress_vlan_id = reader.read("!H")[0]
@@ -426,7 +426,7 @@
         obj = bucket()
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (0 + 2))
+        reader = orig_reader.slice(_len, 2)
         obj.weight = reader.read("!H")[0]
         obj.watch_port = util.unpack_port_no(reader)
         obj.watch_group = reader.read("!L")[0]
@@ -582,7 +582,7 @@
         obj = flow_stats_entry()
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (0 + 2))
+        reader = orig_reader.slice(_length, 2)
         obj.table_id = reader.read("!B")[0]
         reader.skip(1)
         obj.duration_sec = reader.read("!L")[0]
@@ -687,7 +687,7 @@
         obj = group_desc_stats_entry()
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (0 + 2))
+        reader = orig_reader.slice(_length, 2)
         obj.group_type = reader.read("!B")[0]
         reader.skip(1)
         obj.group_id = reader.read("!L")[0]
@@ -762,7 +762,7 @@
         obj = group_stats_entry()
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (0 + 2))
+        reader = orig_reader.slice(_length, 2)
         reader.skip(2)
         obj.group_id = reader.read("!L")[0]
         obj.ref_count = reader.read("!L")[0]
@@ -831,7 +831,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.oxm_list = loxi.generic_util.unpack_list(reader, oxm.oxm.unpack)
         orig_reader.skip_align()
         return obj
@@ -887,7 +887,7 @@
         obj.port = util.unpack_port_no(reader)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (8 + 2))
+        reader = orig_reader.slice(_len, 10)
         reader.skip(6)
         obj.properties = loxi.generic_util.unpack_list(reader, common.queue_prop.unpack)
         return obj
@@ -1245,7 +1245,7 @@
         obj.type = reader.read("!H")[0]
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -1303,7 +1303,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.experimenter = reader.read("!L")[0]
         reader.skip(4)
@@ -1356,7 +1356,7 @@
         assert(_type == 2)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.rate = reader.read("!H")[0]
         reader.skip(6)
@@ -1407,7 +1407,7 @@
         assert(_type == 1)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.rate = reader.read("!H")[0]
         reader.skip(6)