--- a/targets/Xenomai/plc_Xenomai_main.c	Mon Jan 15 14:43:53 2018 +0100
+++ b/targets/Xenomai/plc_Xenomai_main.c	Fri Jan 19 15:12:23 2018 +0100
@@ -363,6 +363,7 @@
     }    /* as plc does not wait for lock. */
 }
 
+#ifndef HAVE_RETAIN
 int CheckRetainBuffer(void)
 {
 	return 1;
@@ -391,3 +392,4 @@
 void InitRetain(void)
 {
 }
+#endif // !HAVE_RETAIN