diff --git a/lib_ppc/board.c b/lib_ppc/board.c
index 5e6e1e6..f273976 100644
--- a/lib_ppc/board.c
+++ b/lib_ppc/board.c
@@ -120,6 +120,10 @@
 #define	TOTAL_MALLOC_LEN	CFG_MALLOC_LEN
 #endif
 
+#if !defined(CFG_MEM_TOP_HIDE)
+#define CFG_MEM_TOP_HIDE	0
+#endif
+
 extern ulong __init_end;
 extern ulong _end;
 ulong monitor_flash_len;