--- a/targets/Linux/plc_Linux_main_retain.c	Sat Jun 23 09:17:20 2018 +0200
+++ b/targets/Linux/plc_Linux_main_retain.c	Tue Jun 26 10:37:36 2018 +0300
@@ -15,7 +15,7 @@
 #include <unistd.h>
 #include "iec_types.h"
 
-int GetRetainSize();
+int GetRetainSize(void);
 
 /* Retain buffer.  */
 FILE *retain_buffer;