diff --git a/lib/replace/libreplace_cc.m4 b/lib/replace/libreplace_cc.m4
index c7550473dda..e316f8b175e 100644
--- a/lib/replace/libreplace_cc.m4
+++ b/lib/replace/libreplace_cc.m4
@@ -63,6 +63,7 @@ AC_SYS_LARGEFILE
 dnl Add #include for broken IRIX header files
 case "$host_os" in
 	*irix6*) AC_ADD_INCLUDE(<standards.h>)
+		AC_N_DEFINE(_XOPEN_SOURCE,600)
 		;;
 	*hpux*)
 		# mmap on HPUX is completely broken...
diff --git a/lib/replace/wscript b/lib/replace/wscript
index 157296b2983..e178cca9cdf 100644
--- a/lib/replace/wscript
+++ b/lib/replace/wscript
@@ -38,6 +38,10 @@ def configure(conf):
         conf.DEFINE('_OSF_SOURCE', 1, add_to_cflags=True)
         conf.DEFINE('_XOPEN_SOURCE', 600, add_to_cflags=True)
 
+    # SCM_RIGHTS is only avail if _XOPEN_SOURCE iѕ defined on IRIX
+    if conf.env['SYSTEM_UNAME_SYSNAME'] == 'IRIX':
+        conf.DEFINE('_XOPEN_SOURCE', 600, add_to_cflags=True)
+
     conf.CHECK_HEADERS('linux/types.h crypt.h locale.h acl/libacl.h compat.h')
     conf.CHECK_HEADERS('acl/libacl.h attr/xattr.h compat.h ctype.h dustat.h')
     conf.CHECK_HEADERS('fcntl.h fnmatch.h glob.h history.h krb5.h langinfo.h')