diff --git a/libs/ardouralsautil/wscript b/libs/ardouralsautil/wscript
index bbf4840261..b1b9bd76af 100644
--- a/libs/ardouralsautil/wscript
+++ b/libs/ardouralsautil/wscript
@@ -42,7 +42,7 @@ def build(bld):
             obj.uselib   = [ 'DBUS' ]
             obj.install_path = os.path.join(bld.env['LIBDIR'])
             obj.defines = [
-                    '_POSIX_SOURCE',
+                    '_DEFAULT_SOURCE',
                     '_XOPEN_SOURCE=500',
                     'ARD_PROG_NAME="ardour-request-device"',
                     'ARD_APPL_NAME="Ardour ALSA Backend"',
diff --git a/libs/pbd/wscript b/libs/pbd/wscript
index 32d6908d92..901fd6abc7 100644
--- a/libs/pbd/wscript
+++ b/libs/pbd/wscript
@@ -105,6 +105,7 @@ def configure(conf):
 
     conf.check(header_name='execinfo.h', define_name='HAVE_EXECINFO',mandatory=False)
     conf.check(header_name='unistd.h', define_name='HAVE_UNISTD',mandatory=False)
+    conf.env.append_value('CFLAGS', "-D_POSIX_C_SOURCE=200809L")
     if not Options.options.ppc:
         conf.check_cc(
                 msg="Checking for function 'posix_memalign' in stdlib.h",