diff --git a/ryu/ofproto/ofproto_v1_2.py b/ryu/ofproto/ofproto_v1_2.py
index 104c585d..652bb100 100644
--- a/ryu/ofproto/ofproto_v1_2.py
+++ b/ryu/ofproto/ofproto_v1_2.py
@@ -543,7 +543,7 @@ OFPCR_ROLE_MASTER = 2  # Full access, at most one master.
 OFPCR_ROLE_SLAVE = 3  # Read-only access.
 
 # struct ofp_packet_in
-OFP_PACKET_IN_PACK_STR = '!IHBB'  # the last 2x is for ofp_packet_in::data
+OFP_PACKET_IN_PACK_STR = '!IHBB'
 OFP_PACKET_IN_SIZE = 24
 assert (calcsize(OFP_PACKET_IN_PACK_STR) + OFP_MATCH_SIZE + OFP_HEADER_SIZE ==
         OFP_PACKET_IN_SIZE)