diff --git a/drivers/mfd/timberdale.h b/drivers/mfd/timberdale.h
index 8d27ffabc25d..902c45120241 100644
--- a/drivers/mfd/timberdale.h
+++ b/drivers/mfd/timberdale.h
@@ -66,7 +66,7 @@
 
 #define CHIPCTLOFFSET	0x800
 #define CHIPCTLEND	0x8ff
-#define CHIPCTLSIZE	(CHIPCTLEND - CHIPCTLOFFSET)
+#define CHIPCTLSIZE	(CHIPCTLEND - CHIPCTLOFFSET + 1)
 
 #define INTCOFFSET	0xc00
 #define INTCEND		0xfff