diff --git a/lib/sockunion.h b/lib/sockunion.h
index 2c79fb5..ea3b833 100644
--- a/lib/sockunion.h
+++ b/lib/sockunion.h
@@ -87,6 +87,7 @@
 extern const char *sockunion2str (const union sockunion *, char *, size_t);
 extern int sockunion_cmp (const union sockunion *, const union sockunion *);
 extern int sockunion_same (const union sockunion *, const union sockunion *);
+extern unsigned int sockunion_hash (const union sockunion *);
 
 extern union sockunion *sockunion_str2su (const char *str);
 extern int sockunion_accept (int sock, union sockunion *);