diff --git a/src/app-layer-dns-common.h b/src/app-layer-dns-common.h
index 9ae04c165d..ab2d8ef118 100644
--- a/src/app-layer-dns-common.h
+++ b/src/app-layer-dns-common.h
@@ -78,12 +78,12 @@ typedef struct DNSHeader_ {
     uint16_t answer_rr;
     uint16_t authority_rr;
     uint16_t additional_rr;
-} DNSHeader;
+} __attribute__((__packed__)) DNSHeader;
 
 typedef struct DNSQueryTrailer_ {
     uint16_t type;
     uint16_t class;
-} DNSQueryTrailer;
+} __attribute__((__packed__)) DNSQueryTrailer;
 
 /** \brief DNS answer header
  *  packed as we don't want alignment to mess up sizeof() */
diff --git a/src/decode-tcp.h b/src/decode-tcp.h
index 067d4a4862..152d5103f4 100644
--- a/src/decode-tcp.h
+++ b/src/decode-tcp.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2010 Open Information Security Foundation
+/* Copyright (C) 2007-2013 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -136,7 +136,7 @@ typedef struct TCPHdr_
     uint16_t th_win;    /**< pkt window */
     uint16_t th_sum;    /**< checksum */
     uint16_t th_urp;    /**< urgent pointer */
-} TCPHdr;
+} __attribute__((__packed__)) TCPHdr;
 
 typedef struct TCPVars_
 {
diff --git a/src/decode-udp.h b/src/decode-udp.h
index 2c3a7845d7..5636c32b0f 100644
--- a/src/decode-udp.h
+++ b/src/decode-udp.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2010 Open Information Security Foundation
+/* Copyright (C) 2007-2013 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -42,7 +42,7 @@ typedef struct UDPHdr_
 	uint16_t uh_dport;  /* destination port */
 	uint16_t uh_len;    /* length */
 	uint16_t uh_sum;    /* checksum */
-} UDPHdr;
+} __attribute__((__packed__)) UDPHdr;
 
 typedef struct UDPVars_
 {