--- ./tools/build/src/tools/builtin.py.orig	2016-09-29 16:03:52.586603000 +0200
+++ tools/build/src/tools/builtin.py	2016-09-29 16:05:12.454463000 +0200
@@ -82,7 +82,7 @@
     feature.compose ("<variant>" + name, explicit_properties.all())
 
 __os_names = """
-    amiga aix bsd cygwin darwin dos emx freebsd hpux iphone linux netbsd
+    amiga aix bsd bsdsunix cygwin darwin dos emx freebsd hpux iphone linux netbsd
     openbsd osf qnx qnxnto sgi solaris sun sunos svr4 sysv ultrix unix unixware
     vms windows
 """.split()
@@ -97,6 +97,7 @@
         elif host_os == 'AS400': host_os = 'unix'
         elif host_os == 'MINGW': host_os = 'windows'
         elif host_os == 'BSDI': host_os = 'bsd'
+        elif host_os == 'BSDSUNIX': host_os = 'bsd'
         elif host_os == 'COHERENT': host_os = 'unix'
         elif host_os == 'DRAGONFLYBSD': host_os = 'bsd'
         elif host_os == 'IRIX': host_os = 'sgi'