diff --git a/chipdrivers.h b/chipdrivers.h
index 9537775..7339e2d 100644
--- a/chipdrivers.h
+++ b/chipdrivers.h
@@ -29,7 +29,8 @@
 int probe_spi_rdid(struct flashchip *flash);
 int probe_spi_rdid4(struct flashchip *flash);
 int probe_spi_rems(struct flashchip *flash);
-int probe_spi_res(struct flashchip *flash);
+int probe_spi_res1(struct flashchip *flash);
+int probe_spi_res2(struct flashchip *flash);
 int spi_write_enable(void);
 int spi_write_disable(void);
 int spi_chip_erase_60(struct flashchip *flash);
diff --git a/flashchips.c b/flashchips.c
index b1af60a..45f4076 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -4665,19 +4665,19 @@
 
 	/* The ST M25P05 is a bit of a problem. It has the same ID as the
 	 * ST M25P05-A in RES mode, but supports only 128 byte writes instead
-	 * of 256 byte writes. We rely heavily on the fact that probe_spi_res
+	 * of 256 byte writes. We rely heavily on the fact that probe_spi_res1
 	 * only is successful if RDID does not work.
 	 */
 	{
 		.vendor		= "ST",
 		.name		= "M25P05.RES",
 		.bustype	= CHIP_BUSTYPE_SPI,
-		.manufacture_id	= ST_ID,
+		.manufacture_id	= 0, /* Not used. */
 		.model_id	= ST_M25P05_RES,
 		.total_size	= 64,
 		.page_size	= 256,
 		.tested		= TEST_UNTESTED,
-		.probe		= probe_spi_res,
+		.probe		= probe_spi_res1,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=
 		{
@@ -4723,12 +4723,12 @@
 		.vendor		= "ST",
 		.name		= "M25P10.RES",
 		.bustype	= CHIP_BUSTYPE_SPI,
-		.manufacture_id	= ST_ID,
+		.manufacture_id	= 0, /* Not used. */
 		.model_id	= ST_M25P10_RES,
 		.total_size	= 128,
 		.page_size	= 256,
 		.tested		= TEST_UNTESTED,
-		.probe		= probe_spi_res,
+		.probe		= probe_spi_res1,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=
 		{
@@ -4798,12 +4798,12 @@
 		.vendor		= "ST",
 		.name		= "M25P40-old",
 		.bustype	= CHIP_BUSTYPE_SPI,
-		.manufacture_id	= ST_ID,
+		.manufacture_id	= 0, /* Not used. */
 		.model_id	= ST_M25P40_RES,
 		.total_size	= 512,
 		.page_size	= 256,
 		.tested		= TEST_UNTESTED,
-		.probe		= probe_spi_res,
+		.probe		= probe_spi_res1,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=
 		{
diff --git a/spi.h b/spi.h
index 1b49d59..5cdf32b 100644
--- a/spi.h
+++ b/spi.h
@@ -27,6 +27,7 @@
 /* Read Electronic ID */
 #define JEDEC_RDID		0x9f
 #define JEDEC_RDID_OUTSIZE	0x01
+/* INSIZE may be 0x04 for some chips*/
 #define JEDEC_RDID_INSIZE	0x03
 
 /* AT25F512A has bit 3 as don't care bit in commands */
@@ -42,6 +43,7 @@
 /* Read Electronic Signature */
 #define JEDEC_RES		0xab
 #define JEDEC_RES_OUTSIZE	0x04
+/* INSIZE may be 0x02 for some chips*/
 #define JEDEC_RES_INSIZE	0x01
 
 /* Write Enable */
diff --git a/spi25.c b/spi25.c
index b45faf8..72940c1 100644
--- a/spi25.c
+++ b/spi25.c
@@ -67,20 +67,20 @@
 	return 0;
 }
 
-static int spi_res(unsigned char *readarr)
+static int spi_res(unsigned char *readarr, int bytes)
 {
 	unsigned char cmd[JEDEC_RES_OUTSIZE] = { JEDEC_RES, 0, 0, 0 };
 	uint32_t readaddr;
 	int ret;
 
-	ret = spi_send_command(sizeof(cmd), JEDEC_RES_INSIZE, cmd, readarr);
+	ret = spi_send_command(sizeof(cmd), bytes, cmd, readarr);
 	if (ret == SPI_INVALID_ADDRESS) {
 		/* Find the lowest even address allowed for reads. */
 		readaddr = (spi_get_valid_read_addr() + 1) & ~1;
 		cmd[1] = (readaddr >> 16) & 0xff,
 		cmd[2] = (readaddr >> 8) & 0xff,
 		cmd[3] = (readaddr >> 0) & 0xff,
-		ret = spi_send_command(sizeof(cmd), JEDEC_RES_INSIZE, cmd, readarr);
+		ret = spi_send_command(sizeof(cmd), bytes, cmd, readarr);
 	}
 	if (ret)
 		return ret;
@@ -235,13 +235,15 @@
 	return 0;
 }
 
-int probe_spi_res(struct flashchip *flash)
+int probe_spi_res1(struct flashchip *flash)
 {
 	unsigned char readarr[3];
 	uint32_t id2;
 	const unsigned char allff[] = {0xff, 0xff, 0xff};
 	const unsigned char all00[] = {0x00, 0x00, 0x00};
 
+	/* We only want one-byte RES if RDID and REMS are unusable. */
+
 	/* Check if RDID is usable and does not return 0xff 0xff 0xff or
 	 * 0x00 0x00 0x00. In that case, RES is pointless.
 	 */
@@ -259,12 +261,13 @@
 		return 0;
 	}
 
-	if (spi_res(readarr))
+	if (spi_res(readarr, 1))
 		return 0;
 
-	/* FIXME: Handle the case where RES gives a 2-byte response. */
 	id2 = readarr[0];
+
 	msg_cdbg("%s: id 0x%x\n", __func__, id2);
+
 	if (id2 != flash->model_id)
 		return 0;
 
@@ -275,6 +278,29 @@
 	return 1;
 }
 
+int probe_spi_res2(struct flashchip *flash)
+{
+	unsigned char readarr[2];
+	uint32_t id1, id2;
+
+	if (spi_res(readarr, 2))
+		return 0;
+
+	id1 = readarr[0];
+	id2 = readarr[1];
+
+	msg_cdbg("%s: id1 0x%x, id2 0x%x\n", __func__, id1, id2);
+
+	if (id1 != flash->manufacture_id || id2 != flash->model_id)
+		return 0;
+
+	/* Print the status register to tell the
+	 * user about possible write protection.
+	 */
+	spi_prettyprint_status_register(flash);
+	return 1;
+}
+
 uint8_t spi_read_status_register(void)
 {
 	const unsigned char cmd[JEDEC_RDSR_OUTSIZE] = { JEDEC_RDSR };