diff --git a/sys/idn.h b/sys/idn.h
new file mode 100644
index 0000000..d8823b5
--- /dev/null
+++ b/sys/idn.h
@@ -0,0 +1,26 @@
+#ifndef LPC_IDN_H_
+#define LPC_IDN_H_ 1
+
+/* --- IDNA Constants ---
+ */
+
+/* idna_stringprep() profiles. */
+
+#define STRINGPREP_NAMEPREP 1
+#define STRINGPREP_SASLPREP 2
+#define STRINGPREP_PLAIN 3
+#define STRINGPREP_TRACE 4
+#define STRINGPREP_KERBEROS5 5
+#define STRINGPREP_XMPP_NODEPREP 6
+#define STRINGPREP_XMPP_RESOURCEPREP 7 
+#define STRINGPREP_ISCSI 8
+
+/* idna_stringprep() flags */
+
+#define STRINGPREP_NO_NFKC_FLAG        (1<<0)
+#define STRINGPREP_NO_BIDI_FLAG        (1<<1)
+#define STRINGPREP_NO_UNASSIGNED_FLAG  (1<<2)
+
+#define STRINGPREP_FLAG_MAX  (1<<2)
+
+#endif