diff --git a/dediprog.c b/dediprog.c
index cf4bd64..1889bfe 100644
--- a/dediprog.c
+++ b/dediprog.c
@@ -55,34 +55,35 @@
 
 //int usb_control_msg(usb_dev_handle *dev, int requesttype, int request, int value, int index, char *bytes, int size, int timeout);
 
-static int dediprog_set_spi_voltage(uint16_t voltage)
+static int dediprog_set_spi_voltage(int millivolt)
 {
 	int ret;
-	unsigned int mv;
+	uint16_t voltage_selector;
 
-	switch (voltage) {
-	case 0x0:
+	switch (millivolt) {
+	case 0:
 		/* Admittedly this one is an assumption. */
-		mv = 0;
+		voltage_selector = 0x0;
 		break;
-	case 0x12:
-		mv = 1800;
+	case 1800:
+		voltage_selector = 0x12;
 		break;
-	case 0x11:
-		mv = 2500;
+	case 2500:
+		voltage_selector = 0x11;
 		break;
-	case 0x10:
-		mv = 3500;
+	case 3500:
+		voltage_selector = 0x10;
 		break;
 	default:
-		msg_perr("Unknown voltage selector 0x%x! Aborting.\n", voltage);
+		msg_perr("Unknown voltage %i mV! Aborting.\n", millivolt);
 		return 1;
 	}
-	msg_pdbg("Setting SPI voltage to %u.%03u V\n", mv / 1000, mv % 1000);
+	msg_pdbg("Setting SPI voltage to %u.%03u V\n", millivolt / 1000,
+		 millivolt % 1000);
 
-	ret = usb_control_msg(dediprog_handle, 0x42, 0x9, voltage, 0xff, NULL, 0x0, DEFAULT_TIMEOUT);
+	ret = usb_control_msg(dediprog_handle, 0x42, 0x9, voltage_selector, 0xff, NULL, 0x0, DEFAULT_TIMEOUT);
 	if (ret != 0x0) {
-		msg_perr("Command Set SPI Voltage 0x%x failed!\n", voltage);
+		msg_perr("Command Set SPI Voltage 0x%x failed!\n", voltage_selector);
 		return 1;
 	}
 	return 0;
@@ -279,13 +280,74 @@
 }
 #endif
 
+static int parse_voltage(char *voltage)
+{
+	char *tmp = NULL;
+	int i;
+	int millivolt;
+	int fraction = 0;
+
+	if (!voltage || !strlen(voltage)) {
+		msg_perr("Empty voltage= specified.\n");
+		return -1;
+	}
+	millivolt = (int)strtol(voltage, &tmp, 0);
+	voltage = tmp;
+	/* Handle "," and "." as decimal point. Everything after it is assumed
+	 * to be in decimal notation.
+	 */
+	if ((*voltage == '.') || (*voltage == ',')) {
+		voltage++;
+		for (i = 0; i < 3; i++) {
+			fraction *= 10;
+			/* Don't advance if the current character is invalid,
+			 * but continue multiplying.
+			 */
+			if ((*voltage < '0') || (*voltage > '9'))
+				continue;
+			fraction += *voltage - '0';
+			voltage++;
+		}
+		/* Throw away remaining digits. */
+		voltage += strspn(voltage, "0123456789");
+	}
+	/* The remaining string must be empty or "mV" or "V". */
+	tolower_string(voltage);
+
+	/* No unit or "V". */
+	if ((*voltage == '\0') || !strncmp(voltage, "v", 1)) {
+		millivolt *= 1000;
+		millivolt += fraction;
+	} else if (!strncmp(voltage, "mv", 2) ||
+		   !strncmp(voltage, "milliv", 6)) {
+		/* No adjustment. fraction is discarded. */
+	} else {
+		/* Garbage at the end of the string. */
+		msg_perr("Garbage voltage= specified.\n");
+		return -1;
+	}
+	return millivolt;
+}
+
 /* URB numbers refer to the first log ever captured. */
 int dediprog_init(void)
 {
 	struct usb_device *dev;
+	char *voltage;
+	int millivolt = 3500;
 
 	msg_pspew("%s\n", __func__);
 
+	voltage = extract_programmer_param("voltage");
+	if (voltage) {
+		millivolt = parse_voltage(voltage);
+		free(voltage);
+		if (millivolt < 0) {
+			return 1;
+		}
+		msg_pinfo("Setting voltage to %i mV\n", millivolt);
+	}
+
 	/* Here comes the USB stuff. */
 	usb_init();
 	usb_find_busses();
@@ -315,7 +377,7 @@
 	if (dediprog_command_c())
 		return 1;
 	/* URB 11. Command Set SPI Voltage. */
-	if (dediprog_set_spi_voltage(0x10))
+	if (dediprog_set_spi_voltage(millivolt))
 		return 1;
 
 	buses_supported = CHIP_BUSTYPE_SPI;
diff --git a/dummyflasher.c b/dummyflasher.c
index 21ee9b4..473e45e 100644
--- a/dummyflasher.c
+++ b/dummyflasher.c
@@ -19,7 +19,6 @@
 
 #include <string.h>
 #include <stdlib.h>
-#include <ctype.h>
 #include "flash.h"
 #include "chipdrivers.h"
 #include "programmer.h"
@@ -61,12 +60,6 @@
 
 static int spi_write_256_chunksize = 256;
 
-static void tolower_string(char *str)
-{
-	for (; *str != '\0'; str++)
-		*str = (char)tolower((unsigned char)*str);
-}
-
 int dummy_init(void)
 {
 	char *bustext = NULL;
diff --git a/flash.h b/flash.h
index 6ac3c1c..250482f 100644
--- a/flash.h
+++ b/flash.h
@@ -197,6 +197,7 @@
 int read_flash_to_file(struct flashchip *flash, char *filename);
 int min(int a, int b);
 int max(int a, int b);
+void tolower_string(char *str);
 char *extract_param(char **haystack, char *needle, char *delim);
 int check_erased_range(struct flashchip *flash, int start, int len);
 int verify_range(struct flashchip *flash, uint8_t *cmpbuf, int start, int len, char *message);
diff --git a/flashrom.8 b/flashrom.8
index 667e06b..0f2a6c4 100644
--- a/flashrom.8
+++ b/flashrom.8
@@ -402,7 +402,20 @@
 (in Hz). The default is the maximum frequency of 8 MHz.
 .TP
 .BR "dediprog " programmer
-No parameters defined yet.
+An optional
+.B voltage
+parameter specifies the voltage the Dediprog should use. The default unit is
+Volt if no unit is specified. You can use
+.BR mV ", " milliVolt ", " V " or " Volt
+as unit specifier. Syntax is
+.sp
+.B "flashrom \-p dediprog:voltage=value"
+.sp
+where
+.B value
+can be any of
+.BR 0V ", " 1.8V ", " 2.5V ", " 3.5V
+or the equivalent in mV.
 .TP
 .BR "rayer_spi " programmer
 The default I/O base address used for the parallel port is 0x378 and you can use
diff --git a/flashrom.c b/flashrom.c
index 4fc8fca..b45ac13 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -29,6 +29,7 @@
 #endif
 #include <string.h>
 #include <stdlib.h>
+#include <ctype.h>
 #include <getopt.h>
 #if HAVE_UTSNAME == 1
 #include <sys/utsname.h>
@@ -615,6 +616,12 @@
 	return i;
 }
 
+void tolower_string(char *str)
+{
+	for (; *str != '\0'; str++)
+		*str = (char)tolower((unsigned char)*str);
+}
+
 char *strcat_realloc(char *dest, const char *src)
 {
 	dest = realloc(dest, strlen(dest) + strlen(src) + 1);