diff --git a/router/connection.go b/router/connection.go
index 488f9a48..64b4ee04 100644
--- a/router/connection.go
+++ b/router/connection.go
@@ -345,6 +345,11 @@ func (conn *LocalConnection) handshake(acceptNewPeer bool) error {
 			return fmt.Errorf("Found unknown remote name: %s at %s", name, conn.remoteTCPAddr)
 		}
 	}
+	if existingConn, found := conn.local.ConnectionTo(name); found {
+		if existingConn.Established() {
+			return fmt.Errorf("Already have connection to %s at %s", name, existingConn.RemoteTCPAddr())
+		}
+	}
 
 	uidStr, err := checkHandshakeStringField("UID", "", handshakeRecv)
 	if err != nil {