diff --git a/spi.h b/spi.h
index 80385fa..4c6ff3e 100644
--- a/spi.h
+++ b/spi.h
@@ -169,9 +169,11 @@
 
 /* Write Extended Address Register */
 #define JEDEC_WRITE_EXT_ADDR_REG	0xC5
+#define ALT_WRITE_EXT_ADDR_REG_17	0x17
 
 /* Read Extended Address Register */
 #define JEDEC_READ_EXT_ADDR_REG		0xC8
+#define ALT_READ_EXT_ADDR_REG_16	0x16
 
 /* Read the memory */
 #define JEDEC_READ		0x03