diff --git a/CHANGELOG b/CHANGELOG
index d8296bd7..3e5433b4 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -238,6 +238,9 @@ HISTORY
 
   ++ Bug fixes:
 
+  2007-06-26 Simon Goldschmidt
+  * udp.h: Fixed bug #20259: struct udp_hdr was lacking the packin defines.
+
   2007-06-25 Simon Goldschmidt
   * udp.c: Fixed bug #20253: icmp_dest_unreach was called with a wrong p->payload
     for udp packets with no matching pcb.
diff --git a/src/include/lwip/udp.h b/src/include/lwip/udp.h
index 5a5bcb32..04b4e757 100644
--- a/src/include/lwip/udp.h
+++ b/src/include/lwip/udp.h
@@ -45,12 +45,20 @@ extern "C" {
 #define UDP_HLEN 8
 
 /* Fields are (of course) in network byte order. */
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
 struct udp_hdr {
   PACK_STRUCT_FIELD(u16_t src);
   PACK_STRUCT_FIELD(u16_t dest);  /* src/dest UDP ports */
   PACK_STRUCT_FIELD(u16_t len);
   PACK_STRUCT_FIELD(u16_t chksum);
 } PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
 
 #define UDP_FLAGS_NOCHKSUM 0x01U
 #define UDP_FLAGS_UDPLITE  0x02U