diff --git a/arbitrile.cpp b/arbitrile.cpp
index 8b43d5be..ac9acc52 100644
--- a/arbitrile.cpp
+++ b/arbitrile.cpp
@@ -26,6 +26,8 @@ struct connection_t {
   int eid;
   /** 1 if this connection mirrored, 0 otherwise. do_unmirror() removes all mirrors by doubling shapes */
   int mirror;
+  bool operator == (const arb::connection_t& b) const { return tie(sid, eid, mirror) == tie(b.sid, b.eid, b.mirror); }
+  bool operator < (const arb::connection_t& b) const { return tie(sid, eid, mirror) < tie(b.sid, b.eid, b.mirror); }
   };
 
 inline void print(hstream& hs, const connection_t& conn) { print(hs, tie(conn.sid, conn.eid, conn.mirror)); }