$NetBSD$

Our irssi installs in $(prefix).

--- src/Makefile.am.orig	2016-07-05 16:40:14.000000000 +0000
+++ src/Makefile.am
@@ -1,6 +1,6 @@
 AM_CFLAGS = $(LIBOTR_CFLAGS) $(LIBGCRYPT_CFLAGS) $(PACKAGE_FLAGS)
 
-IRSSI_DIST=$(oldincludedir)/irssi
+IRSSI_DIST=$(prefix)/include/irssi
 IRSSI_INCLUDE = -I$(IRSSI_DIST) \
 				-I$(IRSSI_DIST)/src \
 				-I$(IRSSI_DIST)/src/fe-common/core \