diff --git a/Makefile.am b/Makefile.am
index 8b1cfb8..9965f7c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,12 +1,20 @@
 AUTOMAKE_OPTIONS=foreign subdir-objects
+
+SUBDIRS = include
+
 bin_PROGRAMS=bgpq4
+
 COMPAT_SOURCES=compat/strlcpy.c
+
 bgpq4_SOURCES=bgpq4.c bgpq4.h config.h bgpq4_printer.c bgpq_expander.c \
     expander_freeall.c expander_freeall.h sx_maxsockbuf.c \
     sx_maxsockbuf.h sx_prefix.c sx_prefix.h sx_report.c sx_report.h \
-    sx_slentry.c sx_slentry.h sys_queue.h sys_tree.h $(COMPAT_SOURCES)
+    sx_slentry.c sx_slentry.h sys_queue.h $(COMPAT_SOURCES)
+
 dist_man8_MANS=bgpq4.8
+
 EXTRA_DIST=bootstrap README.md CHANGES COPYRIGHT bgpq4.spec
+
 MAINTAINERCLEANFILES=configure aclocal.m4 compile \
                      install-sh missing Makefile.in depcomp \
                      stamp-h1 config.h.in
diff --git a/configure.ac b/configure.ac
index 8ce17eb..b0c4779 100644
--- a/configure.ac
+++ b/configure.ac
@@ -33,4 +33,9 @@ AC_CHECK_FUNCS(pledge)
 AC_CHECK_LIB(socket,socket)
 AC_CHECK_LIB(nsl,getaddrinfo)
 
-AC_OUTPUT(Makefile)
+AC_CONFIG_FILES([
+	Makefile
+	include/Makefile
+])
+
+AC_OUTPUT
diff --git a/include/Makefile.am b/include/Makefile.am
new file mode 100644
index 0000000..0aaa784
--- /dev/null
+++ b/include/Makefile.am
@@ -0,0 +1,2 @@
+noinst_HEADERS =
+noinst_HEADERS += sys/tree.h
diff --git a/sys_tree.h b/include/sys/tree.h
similarity index 100%
rename from sys_tree.h
rename to include/sys/tree.h
diff --git a/sx_slentry.h b/sx_slentry.h
index ddbe5e3..01b3825 100644
--- a/sx_slentry.h
+++ b/sx_slentry.h
@@ -10,7 +10,7 @@
 #if HAVE_SYS_TREE_H
 #include <sys/tree.h>
 #else
-#include "sys_tree.h"
+#include <sys/tree.h>
 #endif
 
 struct sx_slentry {