diff --git a/include/unistd.h b/include/unistd.h
index 6d9a6f2db..d89bdb476 100755
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -40,6 +40,7 @@
 #define SI_PROC_ADDR	   1	/* address of process table */
 #define SI_PROC_TAB	   2	/* copy of entire process table */
 #define SI_DMAP_TAB	   3	/* get device <-> driver mappings */
+#define SI_MEM_ALLOC	   4	/* get memory allocation data */
 
 /* NULL must be defined in <unistd.h> according to POSIX Sec. 2.7.1. */
 #define NULL    ((void *)0)