diff --git a/sys/net/rndis.h b/sys/net/rndis.h
index 4c82ca4961ce..ba351479de69 100644
--- a/sys/net/rndis.h
+++ b/sys/net/rndis.h
@@ -111,6 +111,26 @@ struct rndis_packet_msg {
 	uint32_t rm_reserved;
 };
 
+/*
+ * Minimum value for rm_dataoffset, rm_oobdataoffset, and
+ * rm_pktinfooffset.
+ */
+#define	RNDIS_PACKET_MSG_OFFSET_MIN		\
+	(sizeof(struct rndis_packet_msg) -	\
+	 __offsetof(struct rndis_packet_msg, rm_dataoffset))
+
+/* Per-packet-info for RNDIS data message */
+struct rndis_pktinfo {
+	uint32_t rm_size;
+	uint32_t rm_type;
+	uint32_t rm_pktinfooffset;
+	uint8_t rm_data[];
+};
+
+#define	RNDIS_PKTINFO_OFFSET		\
+	__offsetof(struct rndis_pktinfo, rm_data[0])
+#define	RNDIS_PKTINFO_ALIGN		4
+
 /*
  * RNDIS control messages
  */