diff --git a/mps/code/config.h b/mps/code/config.h
index 1dd6a2e07f5..1792e8cbaba 100644
--- a/mps/code/config.h
+++ b/mps/code/config.h
@@ -454,6 +454,7 @@
  *
  * Source      Symbols                   Header        Feature
  * =========== ========================= ============= ====================
+ * eventtxt.c  setenv                    <stdlib.h>    _GNU_SOURCE
  * lockli.c    pthread_mutexattr_settype <pthread.h>   _XOPEN_SOURCE >= 500
  * prmci3li.c  REG_EAX etc.              <ucontext.h>  _GNU_SOURCE
  * prmci6li.c  REG_RAX etc.              <ucontext.h>  _GNU_SOURCE
@@ -472,9 +473,14 @@
 
 #if defined(MPS_OS_LI)
 
+#if defined(_XOPEN_SOURCE) && _XOPEN_SOURCE < 500
+#undef _XOPEN_SOURCE
+#endif
+#if !defined(_XOPEN_SOURCE)
 #define _XOPEN_SOURCE 500
+#endif
 
-#ifndef _GNU_SOURCE
+#if !defined(_GNU_SOURCE)
 #define _GNU_SOURCE
 #endif
 
diff --git a/mps/code/eventtxt.c b/mps/code/eventtxt.c
index bc0d550d122..01b071aee3a 100644
--- a/mps/code/eventtxt.c
+++ b/mps/code/eventtxt.c
@@ -29,13 +29,13 @@
  * $Id$
  */
 
+#include "check.h"
+#include "config.h"
+#include "eventcom.h"
+#include "eventdef.h"
 #include "mps.h"
 #include "mpsavm.h"
 #include "mpscmvff.h"
-#include "check.h"
-#include "config.h"
-#include "eventdef.h"
-#include "eventcom.h"
 #include "table.h"
 #include "testlib.h" /* for ulongest_t and associated print formats */