shrink size of Operand
diff --git a/xbyak/xbyak.h b/xbyak/xbyak.h
index 7b8da5a..6ad3105 100644
--- a/xbyak/xbyak.h
+++ b/xbyak/xbyak.h
@@ -346,8 +346,8 @@
 #endif
 
 class Operand {
-	static const uint8 EXT8BIT = 0x80;
-	unsigned int idx_:8; // 0..31, EXT8BIT = 1 if spl/bpl/sil/dil
+	static const uint8 EXT8BIT = 0x40;
+	unsigned int idx_:7; // 0..31, EXT8BIT = 1 if spl/bpl/sil/dil
 	unsigned int kind_:8;
 	unsigned int bit_:10;
 protected: