Index: uspace/srv/net/include/checksum.h
===================================================================
--- uspace/srv/net/include/checksum.h	(revision 1a0fb3f8aa71e3bb907eb17703615fc685752ca1)
+++ uspace/srv/net/include/checksum.h	(revision 918e9910a408edff4d948fec80491d4c2945dc05)
@@ -41,4 +41,9 @@
 
 #include <sys/types.h>
+
+/** IP checksum value for computed zero checksum.
+ *  Zero is returned as 0xFFFF (not flipped)
+ */
+#define IP_CHECKSUM_ZERO			0xFFFFu
 
 /**	Computes CRC32 value.