diff --git a/examples/reefnet_sensuspro_test.c b/examples/reefnet_sensuspro_test.c
index 09dc08e..b500aa0 100644
--- a/examples/reefnet_sensuspro_test.c
+++ b/examples/reefnet_sensuspro_test.c
@@ -36,8 +36,9 @@ int test_dump_memory (const char* name, const char* filename)
 	message ("time=%lu (%s)\n", (unsigned long)now, datetime);
 
 	message ("device_dump\n");
-	rc = device_dump (device, data, sizeof (data));
-	if (rc < 0) {
+	unsigned int nbytes = 0;
+	rc = device_dump (device, data, sizeof (data), &nbytes);
+	if (rc != DEVICE_STATUS_SUCCESS) {
 		WARNING ("Cannot read memory.");
 		device_close (device);
 		return rc;
@@ -46,7 +47,7 @@ int test_dump_memory (const char* name, const char* filename)
 	message ("Dumping data\n");
 	FILE* fp = fopen (filename, "wb");
 	if (fp != NULL) {
-		fwrite (data, sizeof (unsigned char), rc, fp);
+		fwrite (data, sizeof (unsigned char), nbytes, fp);
 		fclose (fp);
 	}
 
diff --git a/examples/reefnet_sensusultra_test.c b/examples/reefnet_sensusultra_test.c
index 136fd0e..92b59aa 100644
--- a/examples/reefnet_sensusultra_test.c
+++ b/examples/reefnet_sensusultra_test.c
@@ -81,8 +81,9 @@ int test_dump_memory_data (const char* name, const char* filename)
 	message ("time=%lu (%s)\n", (unsigned long)now, datetime);
 
 	message ("device_dump\n");
-	rc = device_dump (device, data, sizeof (data));
-	if (rc < 0) {
+	unsigned int nbytes = 0;
+	rc = device_dump (device, data, sizeof (data), &nbytes);
+	if (rc != DEVICE_STATUS_SUCCESS) {
 		WARNING ("Cannot read memory.");
 		device_close (device);
 		return rc;
@@ -91,7 +92,7 @@ int test_dump_memory_data (const char* name, const char* filename)
 	message ("Dumping data\n");
 	FILE* fp = fopen (filename, "wb");
 	if (fp != NULL) {
-		fwrite (data, sizeof (unsigned char), rc, fp);
+		fwrite (data, sizeof (unsigned char), nbytes, fp);
 		fclose (fp);
 	}
 
diff --git a/examples/suunto_eon_test.c b/examples/suunto_eon_test.c
index 6dffecd..803ba8b 100644
--- a/examples/suunto_eon_test.c
+++ b/examples/suunto_eon_test.c
@@ -21,8 +21,9 @@ int test_dump_memory (const char* name, const char* filename)
 	}
 
 	message ("device_dump\n");
-	rc = device_dump (device, data, sizeof (data));
-	if (rc < 0) {
+	unsigned int nbytes = 0;
+	rc = device_dump (device, data, sizeof (data), &nbytes);
+	if (rc != DEVICE_STATUS_SUCCESS) {
 		WARNING ("Cannot read memory.");
 		device_close (device);
 		return rc;
@@ -31,7 +32,7 @@ int test_dump_memory (const char* name, const char* filename)
 	message ("Dumping data\n");
 	FILE* fp = fopen (filename, "wb");
 	if (fp != NULL) {
-		fwrite (data, sizeof (unsigned char), rc, fp);
+		fwrite (data, sizeof (unsigned char), nbytes, fp);
 		fclose (fp);
 	}
 
diff --git a/examples/uwatec_aladin_test.c b/examples/uwatec_aladin_test.c
index 8e60cf4..b576b07 100644
--- a/examples/uwatec_aladin_test.c
+++ b/examples/uwatec_aladin_test.c
@@ -22,8 +22,9 @@ int test_dump_memory (const char* name, const char* filename)
 	}
 
 	message ("device_dump\n");
-	rc = device_dump (device, data, sizeof (data));
-	if (rc < 0) {
+	unsigned int nbytes = 0;
+	rc = device_dump (device, data, sizeof (data), &nbytes);
+	if (rc != DEVICE_STATUS_SUCCESS) {
 		WARNING ("Cannot read memory.");
 		device_close (device);
 		return rc;
@@ -32,7 +33,7 @@ int test_dump_memory (const char* name, const char* filename)
 	message ("Dumping data\n");
 	FILE* fp = fopen (filename, "wb");
 	if (fp != NULL) {
-		fwrite (data, sizeof (unsigned char), rc, fp);
+		fwrite (data, sizeof (unsigned char), nbytes, fp);
 		fclose (fp);
 	}
 
diff --git a/examples/uwatec_memomouse_test.c b/examples/uwatec_memomouse_test.c
index 770d57e..8329d28 100644
--- a/examples/uwatec_memomouse_test.c
+++ b/examples/uwatec_memomouse_test.c
@@ -22,8 +22,9 @@ int test_dump_memory (const char* name, const char* filename)
 	}
 
 	message ("device_dump\n");
-	rc = device_dump (device, data, sizeof (data));
-	if (rc < 0) {
+	unsigned int nbytes = 0;
+	rc = device_dump (device, data, sizeof (data), &nbytes);
+	if (rc != DEVICE_STATUS_SUCCESS) {
 		WARNING ("Cannot read memory.");
 		device_close (device);
 		return rc;
@@ -32,7 +33,7 @@ int test_dump_memory (const char* name, const char* filename)
 	message ("Dumping data\n");
 	FILE* fp = fopen (filename, "wb");
 	if (fp != NULL) {
-		fwrite (data, sizeof (unsigned char), rc, fp);
+		fwrite (data, sizeof (unsigned char), nbytes, fp);
 		fclose (fp);
 	}
 
diff --git a/examples/uwatec_smart_test.c b/examples/uwatec_smart_test.c
index 761ac0e..136566d 100644
--- a/examples/uwatec_smart_test.c
+++ b/examples/uwatec_smart_test.c
@@ -49,8 +49,9 @@ int test_dump_memory (const char* filename)
 	}
 
 	message ("device_dump\n");
-	rc = device_dump (device, data, size);
-	if (rc < 0) {
+	unsigned int nbytes = 0;
+	rc = device_dump (device, data, size, &nbytes);
+	if (rc != DEVICE_STATUS_SUCCESS) {
 		WARNING ("Cannot read data.");
 		device_close (device);
 		free (data);
@@ -60,7 +61,7 @@ int test_dump_memory (const char* filename)
 	message ("Dumping data\n");
 	FILE* fp = fopen (filename, "wb");
 	if (fp != NULL) {
-		fwrite (data, sizeof (unsigned char), rc, fp);
+		fwrite (data, sizeof (unsigned char), nbytes, fp);
 		fclose (fp);
 	}
 
diff --git a/src/device-private.h b/src/device-private.h
index 056dd41..597a5ef 100644
--- a/src/device-private.h
+++ b/src/device-private.h
@@ -30,7 +30,7 @@ struct device_backend_t {
 
 	device_status_t (*write) (device_t *device, unsigned int address, const unsigned char data[], unsigned int size);
 
-	device_status_t (*dump) (device_t *device, unsigned char data[], unsigned int size);
+	device_status_t (*dump) (device_t *device, unsigned char data[], unsigned int size, unsigned int *result);
 
 	device_status_t (*foreach) (device_t *device, dive_callback_t callback, void *userdata);
 
diff --git a/src/device.c b/src/device.c
index 2c1dfd5..ae47cb9 100644
--- a/src/device.c
+++ b/src/device.c
@@ -90,7 +90,7 @@ device_write (device_t *device, unsigned int address, const unsigned char data[]
 
 
 device_status_t
-device_dump (device_t *device, unsigned char data[], unsigned int size)
+device_dump (device_t *device, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	if (device == NULL)
 		return DEVICE_STATUS_UNSUPPORTED;
@@ -98,7 +98,7 @@ device_dump (device_t *device, unsigned char data[], unsigned int size)
 	if (device->backend->dump == NULL)
 		return DEVICE_STATUS_UNSUPPORTED;
 
-	return device->backend->dump (device, data, size);
+	return device->backend->dump (device, data, size, result);
 }
 
 
diff --git a/src/device.h b/src/device.h
index b908425..a9f496d 100644
--- a/src/device.h
+++ b/src/device.h
@@ -52,7 +52,7 @@ device_status_t device_read (device_t *device, unsigned int address, unsigned ch
 
 device_status_t device_write (device_t *device, unsigned int address, const unsigned char data[], unsigned int size);
 
-device_status_t device_dump (device_t *device, unsigned char data[], unsigned int size);
+device_status_t device_dump (device_t *device, unsigned char data[], unsigned int size, unsigned int *result);
 
 device_status_t device_foreach (device_t *device, dive_callback_t callback, void *userdata);
 
diff --git a/src/oceanic_atom2.c b/src/oceanic_atom2.c
index d974e90..378dd0d 100644
--- a/src/oceanic_atom2.c
+++ b/src/oceanic_atom2.c
@@ -381,7 +381,7 @@ oceanic_atom2_read_ringbuffer (device_t *abstract, unsigned int address, unsigne
 }
 
 static device_status_t
-oceanic_atom2_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+oceanic_atom2_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	if (! device_is_oceanic_atom2 (abstract))
 		return DEVICE_STATUS_TYPE_MISMATCH;
@@ -393,7 +393,10 @@ oceanic_atom2_device_dump (device_t *abstract, unsigned char data[], unsigned in
 	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
-	return OCEANIC_ATOM2_MEMORY_SIZE;
+	if (result)
+		*result = OCEANIC_ATOM2_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
diff --git a/src/reefnet_sensuspro.c b/src/reefnet_sensuspro.c
index 77e6774..1542575 100644
--- a/src/reefnet_sensuspro.c
+++ b/src/reefnet_sensuspro.c
@@ -187,7 +187,7 @@ reefnet_sensuspro_device_handshake (device_t *abstract, unsigned char *data, uns
 
 
 static device_status_t
-reefnet_sensuspro_device_dump (device_t *abstract, unsigned char *data, unsigned int size)
+reefnet_sensuspro_device_dump (device_t *abstract, unsigned char *data, unsigned int size, unsigned int *result)
 {
 	reefnet_sensuspro_device_t *device = (reefnet_sensuspro_device_t*) abstract;
 
@@ -239,7 +239,10 @@ reefnet_sensuspro_device_dump (device_t *abstract, unsigned char *data, unsigned
 		return DEVICE_STATUS_MEMORY;
 	}
 
-	return REEFNET_SENSUSPRO_MEMORY_SIZE;
+	if (result)
+		*result = REEFNET_SENSUSPRO_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
@@ -253,8 +256,8 @@ reefnet_sensuspro_device_foreach (device_t *abstract, dive_callback_t callback,
 
 	unsigned char data[REEFNET_SENSUSPRO_MEMORY_SIZE] = {0};
 
-	int rc = reefnet_sensuspro_device_dump (abstract, data, sizeof (data));
-	if (rc < 0)
+	int rc = reefnet_sensuspro_device_dump (abstract, data, sizeof (data), NULL);
+	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
 	return reefnet_sensuspro_extract_dives (data, sizeof (data), callback, userdata, device->timestamp);
diff --git a/src/reefnet_sensusultra.c b/src/reefnet_sensusultra.c
index 5f47f0b..9136642 100644
--- a/src/reefnet_sensusultra.c
+++ b/src/reefnet_sensusultra.c
@@ -342,7 +342,7 @@ reefnet_sensusultra_page (reefnet_sensusultra_device_t *device, unsigned char *d
 
 
 static device_status_t
-reefnet_sensusultra_device_dump (device_t *abstract, unsigned char *data, unsigned int size)
+reefnet_sensusultra_device_dump (device_t *abstract, unsigned char *data, unsigned int size, unsigned int *result)
 {
 	reefnet_sensusultra_device_t *device = (reefnet_sensusultra_device_t*) abstract;
 
@@ -382,7 +382,10 @@ reefnet_sensusultra_device_dump (device_t *abstract, unsigned char *data, unsign
 		npages++;
 	}
 
-	return REEFNET_SENSUSULTRA_MEMORY_DATA_SIZE;
+	if (result)
+		*result = REEFNET_SENSUSULTRA_MEMORY_DATA_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
diff --git a/src/suunto_d9.c b/src/suunto_d9.c
index db59821..2a64317 100644
--- a/src/suunto_d9.c
+++ b/src/suunto_d9.c
@@ -365,7 +365,7 @@ suunto_d9_device_write (device_t *abstract, unsigned int address, const unsigned
 
 
 static device_status_t
-suunto_d9_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+suunto_d9_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	if (! device_is_suunto_d9 (abstract))
 		return DEVICE_STATUS_TYPE_MISMATCH;
@@ -381,7 +381,10 @@ suunto_d9_device_dump (device_t *abstract, unsigned char data[], unsigned int si
 	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
-	return SUUNTO_D9_MEMORY_SIZE;
+	if (result)
+		*result = SUUNTO_D9_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
diff --git a/src/suunto_eon.c b/src/suunto_eon.c
index 77f97c7..56dc09e 100644
--- a/src/suunto_eon.c
+++ b/src/suunto_eon.c
@@ -118,7 +118,7 @@ suunto_eon_device_close (device_t *abstract)
 
 
 static device_status_t
-suunto_eon_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+suunto_eon_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	suunto_eon_device_t *device = (suunto_eon_device_t*) abstract;
 
@@ -162,7 +162,10 @@ suunto_eon_device_dump (device_t *abstract, unsigned char data[], unsigned int s
 		return DEVICE_STATUS_MEMORY;
 	}
 
-	return SUUNTO_EON_MEMORY_SIZE;
+	if (result)
+		*result = SUUNTO_EON_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
@@ -171,8 +174,8 @@ suunto_eon_device_foreach (device_t *abstract, dive_callback_t callback, void *u
 {
 	unsigned char data[SUUNTO_EON_MEMORY_SIZE] = {0};
 
-	int rc = suunto_eon_device_dump (abstract, data, sizeof (data));
-	if (rc < 0)
+	int rc = suunto_eon_device_dump (abstract, data, sizeof (data), NULL);
+	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
 	return suunto_eon_extract_dives (data, sizeof (data), callback, userdata);
diff --git a/src/suunto_vyper.c b/src/suunto_vyper.c
index 1f9e0e2..f2fca27 100644
--- a/src/suunto_vyper.c
+++ b/src/suunto_vyper.c
@@ -405,7 +405,7 @@ suunto_vyper_device_write (device_t *abstract, unsigned int address, const unsig
 
 
 device_status_t
-suunto_vyper_read_dive (device_t *abstract, unsigned char data[], unsigned int size, int init, device_progress_state_t *progress)
+suunto_vyper_read_dive (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result, int init, device_progress_state_t *progress)
 {
 	suunto_vyper_device_t *device = (suunto_vyper_device_t*) abstract;
 
@@ -494,7 +494,9 @@ suunto_vyper_read_dive (device_t *abstract, unsigned char data[], unsigned int s
 			}
 			message("\"\n");
 #endif
-			return 0;
+			if (result)
+				*result = 0;
+			return DEVICE_STATUS_SUCCESS;
 		}
 
 		progress_event (progress, DEVICE_EVENT_PROGRESS, len);
@@ -521,19 +523,22 @@ suunto_vyper_read_dive (device_t *abstract, unsigned char data[], unsigned int s
 	message("\"\n");
 #endif
 
-	return nbytes;
+	if (result)
+		*result = nbytes;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
 device_status_t
-suunto_vyper_device_read_dive (device_t *abstract, unsigned char data[], unsigned int size, int init)
+suunto_vyper_device_read_dive (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result, int init)
 {
-	return suunto_vyper_read_dive (abstract, data, size, init, NULL);
+	return suunto_vyper_read_dive (abstract, data, size, result, init, NULL);
 }
 
 
 static device_status_t
-suunto_vyper_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+suunto_vyper_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	if (! device_is_suunto_vyper (abstract))
 		return DEVICE_STATUS_TYPE_MISMATCH;
@@ -549,7 +554,10 @@ suunto_vyper_device_dump (device_t *abstract, unsigned char data[], unsigned int
 	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
-	return SUUNTO_VYPER_MEMORY_SIZE;
+	if (result)
+		*result = SUUNTO_VYPER_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
@@ -573,18 +581,19 @@ suunto_vyper_device_foreach (device_t *abstract, dive_callback_t callback, void
 	int rc = 0;
 	unsigned int ndives = 0;
 	unsigned int offset = 0;
-	while ((rc = suunto_vyper_read_dive (abstract, data + offset, sizeof (data) - offset, (ndives == 0), &progress)) > 0) {
-		if (callback && !callback (data + offset, rc, userdata))
+	unsigned int nbytes = 0;
+	while ((rc = suunto_vyper_read_dive (abstract, data + offset, sizeof (data) - offset, &nbytes, (ndives == 0), &progress)) == DEVICE_STATUS_SUCCESS) {
+		if (nbytes == 0)
+			return DEVICE_STATUS_SUCCESS;
+
+		if (callback && !callback (data + offset, nbytes, userdata))
 			return DEVICE_STATUS_SUCCESS;
 
 		ndives++;
-		offset += rc;
+		offset += nbytes;
 	}
 
-	if (rc != 0)
-		return rc;
-
-	return DEVICE_STATUS_SUCCESS;
+	return rc;
 }
 
 
diff --git a/src/suunto_vyper.h b/src/suunto_vyper.h
index 2538e46..883b652 100644
--- a/src/suunto_vyper.h
+++ b/src/suunto_vyper.h
@@ -20,7 +20,7 @@ device_status_t
 suunto_vyper_device_detect_interface (device_t *device);
 
 device_status_t
-suunto_vyper_device_read_dive (device_t *device, unsigned char data[], unsigned int size, int init);
+suunto_vyper_device_read_dive (device_t *device, unsigned char data[], unsigned int size, unsigned int *result, int init);
 
 device_status_t
 suunto_vyper_extract_dives (const unsigned char data[], unsigned int size, dive_callback_t callback, void *userdata);
diff --git a/src/suunto_vyper2.c b/src/suunto_vyper2.c
index 1b9bfef..e21bd99 100644
--- a/src/suunto_vyper2.c
+++ b/src/suunto_vyper2.c
@@ -352,7 +352,7 @@ suunto_vyper2_device_write (device_t *abstract, unsigned int address, const unsi
 
 
 static device_status_t
-suunto_vyper2_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+suunto_vyper2_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	if (! device_is_suunto_vyper2 (abstract))
 		return DEVICE_STATUS_TYPE_MISMATCH;
@@ -368,7 +368,10 @@ suunto_vyper2_device_dump (device_t *abstract, unsigned char data[], unsigned in
 	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
-	return SUUNTO_VYPER2_MEMORY_SIZE;
+	if (result)
+		*result = SUUNTO_VYPER2_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
diff --git a/src/uwatec_aladin.c b/src/uwatec_aladin.c
index 1a44ff8..f6ab5a2 100644
--- a/src/uwatec_aladin.c
+++ b/src/uwatec_aladin.c
@@ -138,7 +138,7 @@ uwatec_aladin_device_set_timestamp (device_t *abstract, unsigned int timestamp)
 
 
 static device_status_t
-uwatec_aladin_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+uwatec_aladin_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	uwatec_aladin_device_t *device = (uwatec_aladin_device_t*) abstract;
 
@@ -197,7 +197,10 @@ uwatec_aladin_device_dump (device_t *abstract, unsigned char data[], unsigned in
 		return DEVICE_STATUS_MEMORY;
 	}
 
-	return UWATEC_ALADIN_MEMORY_SIZE;
+	if (result)
+		*result = UWATEC_ALADIN_MEMORY_SIZE;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
@@ -211,8 +214,8 @@ uwatec_aladin_device_foreach (device_t *abstract, dive_callback_t callback, void
 
 	unsigned char data[UWATEC_ALADIN_MEMORY_SIZE] = {0};
 
-	int rc = uwatec_aladin_device_dump (abstract, data, sizeof (data));
-	if (rc < 0)
+	int rc = uwatec_aladin_device_dump (abstract, data, sizeof (data), NULL);
+	if (rc != DEVICE_STATUS_SUCCESS)
 		return rc;
 
 	return uwatec_aladin_extract_dives (data, sizeof (data), callback, userdata, device->timestamp);
diff --git a/src/uwatec_memomouse.c b/src/uwatec_memomouse.c
index 199a65e..a1cf3a5 100644
--- a/src/uwatec_memomouse.c
+++ b/src/uwatec_memomouse.c
@@ -158,7 +158,7 @@ uwatec_memomouse_confirm (uwatec_memomouse_device_t *device, unsigned char value
 
 
 static device_status_t
-uwatec_memomouse_read_packet (uwatec_memomouse_device_t *device, unsigned char data[], unsigned int size)
+uwatec_memomouse_read_packet (uwatec_memomouse_device_t *device, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	assert (size >= 126 + 2);
 
@@ -197,16 +197,20 @@ uwatec_memomouse_read_packet (uwatec_memomouse_device_t *device, unsigned char d
 		return DEVICE_STATUS_PROTOCOL;
 	}
 
-	return len;
+	if (result)
+		*result = len;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
 static device_status_t
-uwatec_memomouse_read_packet_outer (uwatec_memomouse_device_t *device, unsigned char data[], unsigned int size)
+uwatec_memomouse_read_packet_outer (uwatec_memomouse_device_t *device, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	int rc = 0;
+	unsigned int length = 0;
 	unsigned char package[126 + 2] = {0};
-	while ((rc = uwatec_memomouse_read_packet (device, package, sizeof (package))) < 0) {
+	while ((rc = uwatec_memomouse_read_packet (device, package, sizeof (package), &length)) != DEVICE_STATUS_SUCCESS) {
 		// Automatically discard a corrupted packet, 
 		// and request a new one.
 		if (rc != DEVICE_STATUS_PROTOCOL)
@@ -222,21 +226,24 @@ uwatec_memomouse_read_packet_outer (uwatec_memomouse_device_t *device, unsigned
 	}
 
 #ifndef NDEBUG
-	message ("package(%i)=\"", rc);
-	for (unsigned int i = 0; i < rc; ++i) {
+	message ("package(%i)=\"", length);
+	for (unsigned int i = 0; i < length; ++i) {
 		message ("%02x", package[i + 1]);
 	}
 	message ("\"\n");
 #endif
 
-	if (size >= rc) {
-		memcpy (data, package + 1, rc);
+	if (size >= length) {
+		memcpy (data, package + 1, length);
 	} else {
 		WARNING ("Insufficient buffer space available.");
 		return DEVICE_STATUS_MEMORY;
 	}
 
-	return rc;
+	if (result)
+		*result = length;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
@@ -244,19 +251,20 @@ static device_status_t
 uwatec_memomouse_read_packet_inner (uwatec_memomouse_device_t *device, unsigned char *data[], unsigned int *size, device_progress_state_t *progress)
 {
 	// Read the first package.
+	unsigned int length = 0;
 	unsigned char package[126] = {0};
-	int rca = uwatec_memomouse_read_packet_outer (device, package, sizeof (package));
-	if (rca < 0)
-		return rca;
+	int rc = uwatec_memomouse_read_packet_outer (device, package, sizeof (package), &length);
+	if (rc != DEVICE_STATUS_SUCCESS)
+		return rc;
 
 	// Accept the package.
-	int rcb = uwatec_memomouse_confirm (device, ACK);
-	if (rcb != DEVICE_STATUS_SUCCESS)
-		return rcb;
+	rc = uwatec_memomouse_confirm (device, ACK);
+	if (rc != DEVICE_STATUS_SUCCESS)
+		return rc;
 
 	// Verify the first package contains at least 
 	// the size of the inner package.
-	if (rca < 2) {
+	if (length < 2) {
 		WARNING ("First package is too small.");
 		return DEVICE_STATUS_PROTOCOL;
 	}
@@ -265,7 +273,7 @@ uwatec_memomouse_read_packet_inner (uwatec_memomouse_device_t *device, unsigned
 	unsigned int total = package[0] + (package[1] << 8) + 3;
 
 	progress_set_maximum (progress, total);
-	progress_event (progress, DEVICE_EVENT_PROGRESS, rca);
+	progress_event (progress, DEVICE_EVENT_PROGRESS, length);
 
 	// Allocate memory for the entire package.
 	unsigned char *buffer = malloc (total * sizeof (unsigned char));
@@ -275,28 +283,28 @@ uwatec_memomouse_read_packet_inner (uwatec_memomouse_device_t *device, unsigned
 	}
 
 	// Copy the first package to the new memory buffer.
-	memcpy (buffer, package, rca);
+	memcpy (buffer, package, length);
 
 	// Read the remaining packages.
-	unsigned int nbytes = rca;
+	unsigned int nbytes = length;
 	while (nbytes < total) {
 		// Read the package.
-		rca = uwatec_memomouse_read_packet_outer (device, buffer + nbytes, total - nbytes);
-		if (rca < 0) {
+		rc = uwatec_memomouse_read_packet_outer (device, buffer + nbytes, total - nbytes, &length);
+		if (rc != DEVICE_STATUS_SUCCESS) {
 			free (buffer);
-			return rca;
+			return rc;
 		}
 
 		// Accept the package.
-		rcb = uwatec_memomouse_confirm (device, ACK);
-		if (rcb != DEVICE_STATUS_SUCCESS) {
+		rc = uwatec_memomouse_confirm (device, ACK);
+		if (rc != DEVICE_STATUS_SUCCESS) {
 			free (buffer);
-			return rcb;
+			return rc;
 		}
 
-		progress_event (progress, DEVICE_EVENT_PROGRESS, rca);
+		progress_event (progress, DEVICE_EVENT_PROGRESS, length);
 
-		nbytes += rca;
+		nbytes += length;
 	}
 
 	// Verify the checksum.
@@ -403,7 +411,7 @@ uwatec_memomouse_dump (uwatec_memomouse_device_t *device, unsigned char *data[],
 
 
 static device_status_t
-uwatec_memomouse_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+uwatec_memomouse_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	uwatec_memomouse_device_t *device = (uwatec_memomouse_device_t*) abstract;
 
@@ -426,7 +434,10 @@ uwatec_memomouse_device_dump (device_t *abstract, unsigned char data[], unsigned
 
 	free (buffer);
 
-	return length - 3;
+	if (result)
+		*result = length - 3;
+
+	return DEVICE_STATUS_SUCCESS;
 }
 
 
diff --git a/src/uwatec_smart.c b/src/uwatec_smart.c
index cab254a..e46046d 100644
--- a/src/uwatec_smart.c
+++ b/src/uwatec_smart.c
@@ -392,7 +392,7 @@ uwatec_smart_dump (uwatec_smart_device_t *device, unsigned char *data[], unsigne
 
 
 static device_status_t
-uwatec_smart_device_dump (device_t *abstract, unsigned char data[], unsigned int size)
+uwatec_smart_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
 {
 	uwatec_smart_device_t *device = (uwatec_smart_device_t*) abstract;
 
@@ -415,7 +415,10 @@ uwatec_smart_device_dump (device_t *abstract, unsigned char data[], unsigned int
 
 	free (buffer);
 
-	return length;
+	if (result)
+		*result = length;
+
+	return DEVICE_STATUS_SUCCESS;
 }