diff --git a/src/shearwater_common.c b/src/shearwater_common.c
index c6dafbb..d4b8297 100644
--- a/src/shearwater_common.c
+++ b/src/shearwater_common.c
@@ -342,7 +342,7 @@ shearwater_common_transfer (shearwater_common_device_t *device, const unsigned c
 
 
 dc_status_t
-shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int address, unsigned int size, unsigned int compression)
+shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int address, unsigned int size, unsigned int compression, dc_event_progress_t *progress)
 {
 	dc_device_t *abstract = (dc_device_t *) device;
 	dc_status_t rc = DC_STATUS_SUCCESS;
@@ -370,9 +370,11 @@ shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buf
 	}
 
 	// Enable progress notifications.
-	dc_event_progress_t progress = EVENT_PROGRESS_INITIALIZER;
-	progress.maximum = 3 + size + 1;
-	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+	unsigned int initial = 0, current = 0, maximum = 3 + size + 1;
+	if (progress) {
+		initial = progress->current;
+		device_event_emit (abstract, DC_EVENT_PROGRESS, progress);
+	}
 
 	// Transfer the init request.
 	rc = shearwater_common_transfer (device, req_init, sizeof (req_init), response, 3, &n);
@@ -387,8 +389,11 @@ shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buf
 	}
 
 	// Update and emit a progress event.
-	progress.current += 3;
-	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+	if (progress) {
+		current += 3;
+		progress->current = initial + STEP (current, maximum);
+		device_event_emit (abstract, DC_EVENT_PROGRESS, progress);
+	}
 
 	unsigned int done = 0;
 	unsigned char block = 1;
@@ -415,8 +420,11 @@ shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buf
 		}
 
 		// Update and emit a progress event.
-		progress.current += length;
-		device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+		if (progress) {
+			current += length;
+			progress->current = initial + STEP (current, maximum);
+			device_event_emit (abstract, DC_EVENT_PROGRESS, progress);
+		}
 
 		if (compression) {
 			if (shearwater_common_decompress_lre (response + 2, length, buffer, &done) != 0) {
@@ -454,8 +462,11 @@ shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buf
 	}
 
 	// Update and emit a progress event.
-	progress.current += 1;
-	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+	if (progress) {
+		current += 1;
+		progress->current = initial + STEP (current, maximum);
+		device_event_emit (abstract, DC_EVENT_PROGRESS, progress);
+	}
 
 	return DC_STATUS_SUCCESS;
 }
diff --git a/src/shearwater_common.h b/src/shearwater_common.h
index 2283154..4253a00 100644
--- a/src/shearwater_common.h
+++ b/src/shearwater_common.h
@@ -39,6 +39,9 @@ extern "C" {
 #define PERDIX   5
 #define PERDIXAI 6
 
+#define NSTEPS    10000
+#define STEP(i,n) ((NSTEPS * (i) + (n) / 2) / (n))
+
 typedef struct shearwater_common_device_t {
 	dc_device_t base;
 	dc_serial_t *port;
@@ -54,7 +57,7 @@ dc_status_t
 shearwater_common_transfer (shearwater_common_device_t *device, const unsigned char input[], unsigned int isize, unsigned char output[], unsigned int osize, unsigned int *actual);
 
 dc_status_t
-shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int address, unsigned int size, unsigned int compression);
+shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int address, unsigned int size, unsigned int compression, dc_event_progress_t *progress);
 
 dc_status_t
 shearwater_common_identifier (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int id);
diff --git a/src/shearwater_petrel.c b/src/shearwater_petrel.c
index 3b60bf4..46a7582 100644
--- a/src/shearwater_petrel.c
+++ b/src/shearwater_petrel.c
@@ -168,6 +168,11 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 		return DC_STATUS_NOMEMORY;
 	}
 
+	// Enable progress notifications.
+	unsigned int current = 0, maximum = 0;
+	dc_event_progress_t progress = EVENT_PROGRESS_INITIALIZER;
+	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+
 	// Read the serial number.
 	rc = shearwater_common_identifier (&device->base, buffer, ID_SERIAL);
 	if (rc != DC_STATUS_SUCCESS) {
@@ -240,8 +245,16 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 	device_event_emit (abstract, DC_EVENT_DEVINFO, &devinfo);
 
 	while (1) {
+		// Update the progress state.
+		// Assume the worst case scenario of a full manifest, and adjust the
+		// value with the actual number of dives after the manifest has been
+		// processed.
+		maximum += 1 + RECORD_COUNT;
+
 		// Download a manifest.
-		rc = shearwater_common_download (&device->base, buffer, MANIFEST_ADDR, MANIFEST_SIZE, 0);
+		progress.current = NSTEPS * current;
+		progress.maximum = NSTEPS * maximum;
+		rc = shearwater_common_download (&device->base, buffer, MANIFEST_ADDR, MANIFEST_SIZE, 0, &progress);
 		if (rc != DC_STATUS_SUCCESS) {
 			ERROR (abstract->context, "Failed to download the manifest.");
 			dc_buffer_free (buffer);
@@ -270,6 +283,10 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 			count++;
 		}
 
+		// Update the progress state.
+		current += 1;
+		maximum -= RECORD_COUNT - count;
+
 		// Append the manifest records to the main buffer.
 		if (!dc_buffer_append (manifests, data, count * RECORD_SIZE)) {
 			ERROR (abstract->context, "Insufficient buffer space available.");
@@ -283,6 +300,11 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 			break;
 	}
 
+	// Update and emit a progress event.
+	progress.current = NSTEPS * current;
+	progress.maximum = NSTEPS * maximum;
+	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+
 	// Cache the buffer pointer and size.
 	unsigned char *data = dc_buffer_get_data (manifests);
 	unsigned int size = dc_buffer_get_size (manifests);
@@ -293,7 +315,9 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 		unsigned int address = array_uint32_be (data + offset + 20);
 
 		// Download the dive.
-		rc = shearwater_common_download (&device->base, buffer, DIVE_ADDR + address, DIVE_SIZE, 1);
+		progress.current = NSTEPS * current;
+		progress.maximum = NSTEPS * maximum;
+		rc = shearwater_common_download (&device->base, buffer, DIVE_ADDR + address, DIVE_SIZE, 1, &progress);
 		if (rc != DC_STATUS_SUCCESS) {
 			ERROR (abstract->context, "Failed to download the dive.");
 			dc_buffer_free (buffer);
@@ -301,6 +325,9 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 			return rc;
 		}
 
+		// Update the progress state.
+		current += 1;
+
 		unsigned char *buf = dc_buffer_get_data (buffer);
 		unsigned int len = dc_buffer_get_size (buffer);
 		if (callback && !callback (buf, len, buf + 12, sizeof (device->fingerprint), userdata))
@@ -309,6 +336,11 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 		offset += RECORD_SIZE;
 	}
 
+	// Update and emit a progress event.
+	progress.current = NSTEPS * current;
+	progress.maximum = NSTEPS * maximum;
+	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
+
 	dc_buffer_free (manifests);
 	dc_buffer_free (buffer);
 
diff --git a/src/shearwater_predator.c b/src/shearwater_predator.c
index 3cc79f1..a47d414 100644
--- a/src/shearwater_predator.c
+++ b/src/shearwater_predator.c
@@ -133,7 +133,12 @@ shearwater_predator_device_dump (dc_device_t *abstract, dc_buffer_t *buffer)
 		return DC_STATUS_NOMEMORY;
 	}
 
-	return shearwater_common_download (device, buffer, 0xDD000000, SZ_MEMORY, 0);
+	// Enable progress notifications.
+	dc_event_progress_t progress = EVENT_PROGRESS_INITIALIZER;
+	progress.current = 0;
+	progress.maximum = NSTEPS;
+
+	return shearwater_common_download (device, buffer, 0xDD000000, SZ_MEMORY, 0, &progress);
 }