diff --git a/net/6lowpan/nhc_udp.c b/net/6lowpan/nhc_udp.c
index 72d0b57..69537a2 100644
--- a/net/6lowpan/nhc_udp.c
+++ b/net/6lowpan/nhc_udp.c
@@ -17,7 +17,27 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_UDP_IDLEN	1
+#define LOWPAN_NHC_UDP_MASK		0xF8
+#define LOWPAN_NHC_UDP_ID		0xF0
+#define LOWPAN_NHC_UDP_IDLEN		1
+
+#define LOWPAN_NHC_UDP_4BIT_PORT	0xF0B0
+#define LOWPAN_NHC_UDP_4BIT_MASK	0xFFF0
+#define LOWPAN_NHC_UDP_8BIT_PORT	0xF000
+#define LOWPAN_NHC_UDP_8BIT_MASK	0xFF00
+
+/* values for port compression, _with checksum_ ie bit 5 set to 0 */
+
+/* all inline */
+#define LOWPAN_NHC_UDP_CS_P_00	0xF0
+/* source 16bit inline, dest = 0xF0 + 8 bit inline */
+#define LOWPAN_NHC_UDP_CS_P_01	0xF1
+/* source = 0xF0 + 8bit inline, dest = 16 bit inline */
+#define LOWPAN_NHC_UDP_CS_P_10	0xF2
+/* source & dest = 0xF0B + 4bit inline */
+#define LOWPAN_NHC_UDP_CS_P_11	0xF3
+/* checksum elided */
+#define LOWPAN_NHC_UDP_CS_C	0x04
 
 static int udp_uncompress(struct sk_buff *skb, size_t needed)
 {