diff --git a/p4app/controller.py b/p4app/controller.py
index e7af145..5b7aac5 100644
--- a/p4app/controller.py
+++ b/p4app/controller.py
@@ -248,13 +248,13 @@ class L2Controller(object):
 
             ether_part.type = cpu_header.type
 
-            bits = 0
+            sz = 0
             for field in CpuHeader.fields_desc:
-                bits += field.sz
+                sz += field.sz
 
-            shift_by = (bits/8) -1
+            shift_by = (sz*8) -1
 
-            log.debug("Len of cpu= {}, {}, shift={}".format(bits, bits/8, shift_by))
+            log.debug("Len of cpu= {}, {}, shift={}".format(sz, shift_by))
 
             ether_orig = Ether(src=packet.src, dst=packet.dst, type=0x86dd)
             orig_packet = ether_orig / IPv6(packet.load[shift_by:])