diff --git a/devcmd.c b/devcmd.c
index 586ba62..3b5df61 100644
--- a/devcmd.c
+++ b/devcmd.c
@@ -82,7 +82,7 @@ int cmd_md(char **arg)
 	reader_set_repeat("md 0x%x 0x%x", offset + length, length);
 
 	while (length) {
-		uint8_t buf[128];
+		uint8_t buf[4096];
 		int blen = length > sizeof(buf) ? sizeof(buf) : length;
 
 		if (device_default->readmem(device_default,
@@ -450,7 +450,7 @@ int cmd_hexout(char **arg)
 		return -1;
 
 	while (length) {
-		uint8_t buf[128];
+		uint8_t buf[4096];
 		int count = length;
 
 		if (count > sizeof(buf))
diff --git a/fet.c b/fet.c
index bd1d76c..d299c2b 100644
--- a/fet.c
+++ b/fet.c
@@ -32,9 +32,10 @@
 #include "fet_error.h"
 #include "fet_db.h"
 #include "output.h"
+#include "opdb.h"
 
 #define MAX_PARAMS		16
-#define BLOCK_SIZE              64
+#define MAX_BLOCK_SIZE		4096
 
 struct fet_device {
 	struct device                   base;
@@ -357,10 +358,10 @@ static int send_command(struct fet_device *dev, int command_code,
 		        const uint32_t *params, int nparams,
 			const uint8_t *extra, int exlen)
 {
-	uint8_t datapkt[256];
+	uint8_t datapkt[MAX_BLOCK_SIZE * 2];
 	int len = 0;
 
-	uint8_t buf[512];
+	uint8_t buf[MAX_BLOCK_SIZE * 3];
 	uint16_t cksum;
 	int i = 0;
 	int j;
@@ -758,10 +759,23 @@ static int write_byte(struct fet_device *dev, address_t addr, uint8_t value)
 	return 0;
 }
 
+static int get_adjusted_block_size(void)
+{
+	int block_size = opdb_get_numeric("fet_block_size") & ~1;
+
+	if (block_size < 2)
+		block_size = 2;
+	if (block_size > MAX_BLOCK_SIZE)
+		block_size = MAX_BLOCK_SIZE;
+
+	return block_size;
+}
+
 int fet_readmem(device_t dev_base, address_t addr, uint8_t *buffer,
 		address_t count)
 {
 	struct fet_device *dev = (struct fet_device *)dev_base;
+	int block_size = get_adjusted_block_size();
 
 	if (addr & 1) {
 		if (read_byte(dev, addr, buffer) < 0)
@@ -772,7 +786,7 @@ int fet_readmem(device_t dev_base, address_t addr, uint8_t *buffer,
 	}
 
 	while (count > 1) {
-		int plen = count > BLOCK_SIZE ? BLOCK_SIZE : count;
+		int plen = count > block_size ? block_size : count;
 
 		plen &= ~0x1;
 
@@ -804,6 +818,7 @@ int fet_writemem(device_t dev_base, address_t addr,
 		 const uint8_t *buffer, address_t count)
 {
 	struct fet_device *dev = (struct fet_device *)dev_base;
+	int block_size = get_adjusted_block_size();
 
 	if (addr & 1) {
 		if (write_byte(dev, addr, *buffer) < 0)
@@ -814,7 +829,7 @@ int fet_writemem(device_t dev_base, address_t addr,
 	}
 
 	while (count > 1) {
-		int plen = count > BLOCK_SIZE ? BLOCK_SIZE : count;
+		int plen = count > block_size ? block_size : count;
 		int ret;
 
 		plen &= ~0x1;
diff --git a/mspdebug.man b/mspdebug.man
index 6fd4801..7881af2 100644
--- a/mspdebug.man
+++ b/mspdebug.man
@@ -430,6 +430,10 @@ The following are all valid examples of address expressions:
 MSPDebug's behaviour can be configured via the following variables:
 .IP "\fBcolor\fR (boolean)"
 If true, MSPDebug will colorize debugging output.
+.IP "\fBfet_block_size\fR (numeric)"
+Change the size of the buffer used to transfer memory to and from the
+FET. Increasing the value from the default of 64 will improve transfer
+speed, but may cause problems with some chips.
 .IP "\fBgdb_loop\fR (boolean)"
 Automatically restart the GDB server after disconnection. If this
 option is set, then the GDB server keeps running until an error occurs,
diff --git a/opdb.c b/opdb.c
index 6a0c77a..1f28ee4 100644
--- a/opdb.c
+++ b/opdb.c
@@ -55,6 +55,17 @@ const static struct opdb_key keys[] = {
 		.defval = {
 			.numeric = 10
 		}
+	},
+	{
+		.name = "fet_block_size",
+		.type = OPDB_TYPE_NUMERIC,
+		.help =
+"Size of buffer used for memory transfers to and from the FET device.\n"
+"Increasing this value will result in faster transfers, but may cause\n"
+"problems with some chips.\n",
+		.defval = {
+			.numeric = 64
+		}
 	}
 };
 
diff --git a/prog.h b/prog.h
index 0b3d82a..a531f66 100644
--- a/prog.h
+++ b/prog.h
@@ -19,7 +19,7 @@
 #ifndef PROG_H_
 #define PROG_H_
 
-#define PROG_BUFSIZE    128
+#define PROG_BUFSIZE    4096
 
 struct prog_data {
 	uint8_t         buf[PROG_BUFSIZE];