diff --git a/firmware/hackrf_usb/usb_api_sweep.c b/firmware/hackrf_usb/usb_api_sweep.c
index 88a065d1..434b7fdc 100644
--- a/firmware/hackrf_usb/usb_api_sweep.c
+++ b/firmware/hackrf_usb/usb_api_sweep.c
@@ -40,11 +40,15 @@ static uint64_t sweep_freq;
 bool odd = true;
 static uint16_t frequencies[MAX_FREQ_COUNT];
 static uint16_t frequency_count = 0;
+static uint32_t dwell_blocks = 0;
 
 usb_request_status_t usb_vendor_request_init_sweep(
 		usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage)
 {
+	uint32_t dwell_time;
 	if (stage == USB_TRANSFER_STAGE_SETUP) {
+		dwell_time = (endpoint->setup.index << 16) | endpoint->setup.value;
+		dwell_blocks = dwell_time / 0x4000;
 		frequency_count = endpoint->setup.length / sizeof(uint16_t);
 		usb_transfer_schedule_block(endpoint->out, &frequencies,
 									endpoint->setup.length, NULL, NULL);
@@ -95,7 +99,7 @@ void sweep_mode(void) {
 			transfer = false;
 		}
 
-		if (blocks_queued > 2) {
+		if (blocks_queued >= dwell_blocks) {
 			if(++ifreq >= frequency_count)
 				ifreq = 0;
 			sweep_freq = frequencies[ifreq];
diff --git a/host/hackrf-tools/CMakeLists.txt b/host/hackrf-tools/CMakeLists.txt
index cc7ff9be..82ea47d8 100644
--- a/host/hackrf-tools/CMakeLists.txt
+++ b/host/hackrf-tools/CMakeLists.txt
@@ -24,7 +24,7 @@
 cmake_minimum_required(VERSION 2.8)
 project(hackrf-tools C)
 set(MAJOR_VERSION 0)
-set(MINOR_VERSION 4)
+set(MINOR_VERSION 5)
 set(PACKAGE hackrf-tools)
 set(VERSION_STRING ${MAJOR_VERSION}.${MINOR_VERSION})
 set(VERSION ${VERSION_STRING})
diff --git a/host/hackrf-tools/src/hackrf_sweep.c b/host/hackrf-tools/src/hackrf_sweep.c
index dda62c1d..59127e7d 100644
--- a/host/hackrf-tools/src/hackrf_sweep.c
+++ b/host/hackrf-tools/src/hackrf_sweep.c
@@ -94,6 +94,8 @@ int gettimeofday(struct timeval *tv, void* ignored) {
 #define FREQ_STEP (DEFAULT_SAMPLE_RATE_HZ / FREQ_ONE_MHZ)
 #define MAX_FREQ_COUNT 1000
 
+#define DEFAULT_DWELL_TIME 0x4000
+
 #if defined _WIN32
 	#define sleep(a) Sleep( (a*1000) )
 #endif
@@ -239,6 +241,7 @@ static void usage() {
 	fprintf(stderr, "\t[-l gain_db] # RX LNA (IF) gain, 0-40dB, 8dB steps\n");
 	fprintf(stderr, "\t[-g gain_db] # RX VGA (baseband) gain, 0-62dB, 2dB steps\n");
 	fprintf(stderr, "\t[-x gain_db] # TX VGA (IF) gain, 0-47dB, 1dB steps\n");
+	fprintf(stderr, "\t[-s dwell_time] # Dwell time in samples, 0-%lu\n", (uint64_t)1<<32);
 }
 
 static hackrf_device* device = NULL;
@@ -270,8 +273,9 @@ int main(int argc, char** argv) {
 	float time_diff;
 	unsigned int lna_gain=16, vga_gain=20, txvga_gain=0;
 	uint16_t frequencies[MAX_FREQ_COUNT];
+	uint32_t dwell_time = DEFAULT_DWELL_TIME;
 
-	while( (opt = getopt(argc, argv, "a:f:p:l:g:x:d:")) != EOF ) {
+	while( (opt = getopt(argc, argv, "a:f:p:l:g:x:d:s:")) != EOF ) {
 		result = HACKRF_SUCCESS;
 		switch( opt ) 
 		{
@@ -316,6 +320,10 @@ int main(int argc, char** argv) {
 			result = parse_u32(optarg, &txvga_gain);
 			break;
 
+		case 's':
+			result = parse_u32(optarg, &dwell_time);
+			break;
+
 		default:
 			fprintf(stderr, "unknown argument '-%c %s'\n", opt, optarg);
 			usage();
@@ -335,6 +343,11 @@ int main(int argc, char** argv) {
 	if (vga_gain % 2)
 		fprintf(stderr, "warning: vga_gain (-g) must be a multiple of 2\n");
 
+	if (dwell_time % 0x4000) {
+		fprintf(stderr, "warning: dwell_time (-s) must be a multiple of 16384\n");
+		return EXIT_FAILURE;
+	}
+
 	if( amp ) {
 		if( amp_enable > 1 ) {
 			fprintf(stderr, "argument error: amp_enable shall be 0 or 1.\n");
@@ -433,8 +446,7 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
-	/* DGS FIXME: allow upper and lower frequencies to be set */
-	result = hackrf_init_sweep(device, frequencies, ifreq);
+	result = hackrf_init_sweep(device, frequencies, ifreq, dwell_time);
 	if( result != HACKRF_SUCCESS ) {
 		fprintf(stderr, "hackrf_init_sweep() failed: %s (%d)\n",
 			   hackrf_error_name(result), result);
diff --git a/host/libhackrf/src/hackrf.c b/host/libhackrf/src/hackrf.c
index 539fd0a7..fffb04e5 100644
--- a/host/libhackrf/src/hackrf.c
+++ b/host/libhackrf/src/hackrf.c
@@ -1699,7 +1699,7 @@ uint32_t ADDCALL hackrf_compute_baseband_filter_bw(const uint32_t bandwidth_hz)
 
 int ADDCALL hackrf_init_sweep(hackrf_device* device,
 							  uint16_t* frequency_list,
-							  int length)
+							  int length, uint32_t dwell_time)
 {
 	int result, i;
 	int size = length * sizeof(frequency_list[0]);
@@ -1711,8 +1711,8 @@ int ADDCALL hackrf_init_sweep(hackrf_device* device,
 		device->usb_device,
 		LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
 		HACKRF_VENDOR_REQUEST_INIT_SWEEP,
-		0,
-		0,
+		dwell_time & 0xff,
+		(dwell_time >> 16) & 0xff,
 		(unsigned char*)frequency_list,
 		size,
 		0
diff --git a/host/libhackrf/src/hackrf.h b/host/libhackrf/src/hackrf.h
index 54ad7092..a318f6ed 100644
--- a/host/libhackrf/src/hackrf.h
+++ b/host/libhackrf/src/hackrf.h
@@ -199,7 +199,7 @@ extern ADDAPI uint32_t ADDCALL hackrf_compute_baseband_filter_bw(const uint32_t
 /* Start scan mode */
 extern ADDAPI int ADDCALL hackrf_init_sweep(hackrf_device* device,
 											uint16_t* frequency_list,
-											int length);
+											int length, uint32_t dwell_time);
 
 #ifdef __cplusplus
 } // __cplusplus defined.