diff --git a/flash.h b/flash.h
index e51b6d4..20db343 100644
--- a/flash.h
+++ b/flash.h
@@ -83,6 +83,7 @@
 #define FEATURE_ADDR_SHIFTED	(1 << 5)
 #define FEATURE_WRSR_EWSR	(1 << 6)
 #define FEATURE_WRSR_WREN	(1 << 7)
+#define FEATURE_OTP		(1 << 8)
 #define FEATURE_WRSR_EITHER	(FEATURE_WRSR_EWSR | FEATURE_WRSR_WREN)
 
 struct flashctx;
diff --git a/flashchips.c b/flashchips.c
index ca1c57f..c6bff8d 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -1120,7 +1120,8 @@
 		.model_id	= AMIC_A25L032,
 		.total_size	= 4096,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 64B total; read 0x4B, 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -1158,7 +1159,8 @@
 		.model_id	= AMIC_A25LQ032,
 		.total_size	= 4096,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 64B total; read 0x4B, 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -1315,7 +1317,8 @@
 		.model_id	= ATMEL_AT25DF021,
 		.total_size	= 256,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 128B total, 64B pre-programmed; read 0x77; write 0x9B */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -1543,7 +1546,8 @@
 		.model_id	= ATMEL_AT25DF321A,
 		.total_size	= 4096,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 128B total, 64B pre-programmed; read 0x77; write 0x9B */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_OK_PROBE,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -1619,7 +1623,8 @@
 		.model_id	= ATMEL_AT25DQ161,
 		.total_size	= 2048,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 128B total, 64B pre-programmed; read 0x77; write 0x9B */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -1657,7 +1662,8 @@
 		.model_id	= ATMEL_AT25F512B,
 		.total_size	= 64,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 128B total, 64B pre-programmed; read 0x77; write 0x9B */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -2168,6 +2174,8 @@
 		.model_id	= ATMEL_AT45DB321D,
 		.total_size	= 4096 /* Size can only be determined from status register */,
 		.page_size	= 512 /* Size can only be determined from status register */,
+		/* OTP: 128B total, 64B pre-programmed; read 0x77; write 0x9B */
+		.feature_bits	= FEATURE_OTP,
 		.tested		= TEST_BAD_READ,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3236,8 +3244,8 @@
 		.model_id	= EON_EN25Q40,
 		.total_size	= 512,
 		.page_size	= 256,
-		/* TODO: chip features 256-byte one-time programmable region */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 256B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3271,8 +3279,8 @@
 		.model_id	= EON_EN25Q80,
 		.total_size	= 1024,
 		.page_size	= 256,
-		/* TODO: chip features 256-byte one-time programmable region */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 256B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3308,9 +3316,8 @@
 		.model_id	= EON_EN25Q16,
 		.total_size	= 2048,
 		.page_size	= 256,
-		/* TODO: EN25D16 features 512-byte one-time programmable region,
-		 * EN25Q16 features a 128-byte one-time programmable region */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: D16 512B/Q16 128B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3348,8 +3355,8 @@
 		.model_id	= EON_EN25Q32,
 		.total_size	= 4096,
 		.page_size	= 256,
-		/* TODO: chip features 512-byte one-time programmable region */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 512B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3383,8 +3390,8 @@
 		.model_id	= EON_EN25Q64,
 		.total_size	= 8192,
 		.page_size	= 256,
-		/* TODO: chip features 512-byte one-time programmable region */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 512B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3418,8 +3425,8 @@
 		.model_id	= EON_EN25Q128,
 		.total_size	= 16384,
 		.page_size	= 256,
-		/* TODO: chip features 512-byte one-time programmable region */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 512B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -3452,10 +3459,9 @@
 		.model_id	= EON_EN25QH16,
 		.total_size	= 2048,
 		.page_size	= 256,
-		/* TODO: chip features 512-byte one-time programmable region
-		 * and supports SFDP.
-		 */
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* supports SFDP */
+		/* OTP: 512B total; enter 0x3A */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -7092,6 +7098,8 @@
 		.model_id	= ST_M25PX16,
 		.total_size	= 2048,
 		.page_size	= 256,
+		/* OTP: 64B total; read 0x4B; write 0x42 */
+		.feature_bits	= FEATURE_OTP,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -7960,7 +7968,8 @@
 		.model_id	= WINBOND_NEX_W25Q80,
 		.total_size	= 1024,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -7997,7 +8006,8 @@
 		.model_id	= WINBOND_NEX_W25Q16,
 		.total_size	= 2048,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -8034,7 +8044,8 @@
 		.model_id	= WINBOND_NEX_W25Q32,
 		.total_size	= 4096,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -8071,7 +8082,8 @@
 		.model_id	= WINBOND_NEX_W25Q64,
 		.total_size	= 8192,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -8107,7 +8119,8 @@
 		.model_id	= WINBOND_NEX_W25Q128,
 		.total_size	= 16384,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN,
+		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42 */
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
 		.tested		= TEST_OK_PROBE,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
diff --git a/flashrom.8 b/flashrom.8
index 2f23cb8..e5f9a29 100644
--- a/flashrom.8
+++ b/flashrom.8
@@ -670,6 +670,19 @@
 More information about flashrom on laptops is available from
 .sp
 .B "  http://www.flashrom.org/Laptops"
+.SS
+One-time programmable (OTP) memory and unique IDs
+.sp
+Some flash chips contain OTP memory often denoted as "security registers".
+They usually have a capacity in the range of some bytes to a few hundred
+bytes and can be used to give devices unique IDs etc. flashrom is not able
+to read or write these memories and may therefore not be able to duplicate a
+chip completely. For chip types known to include OTP memories a warning is
+printed when they are detected.
+.sp
+Similar to OTP memories are unique, factory programmed, unforgeable IDs.
+They are not modifiable by the user at all.
+.RE
 .SH LICENSE
 .B flashrom
 is covered by the GNU General Public License (GPL), version 2. Some files are
diff --git a/flashrom.c b/flashrom.c
index ee68344..a378e51 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1560,6 +1560,13 @@
 
 void check_chip_supported(const struct flashctx *flash)
 {
+	if (flash->feature_bits & FEATURE_OTP) {
+		msg_cdbg("This chip may contain one-time programmable memory. "
+			 "flashrom cannot read\nand may never be able to write "
+			 "it, hence it may not be able to completely\n"
+			 "clone the contents of this chip (see man page for "
+			 "details).\n");
+	}
 	if (TEST_OK_MASK != (flash->tested & TEST_OK_MASK)) {
 		msg_cinfo("===\n");
 		if (flash->tested & TEST_BAD_MASK) {