diff --git a/lib/libusb/Makefile b/lib/libusb/Makefile
index 8d7861918d1a..538b8e6d3e52 100644
--- a/lib/libusb/Makefile
+++ b/lib/libusb/Makefile
@@ -48,6 +48,7 @@ MLINKS += libusb.3 libusb_get_bus_number.3
 MLINKS += libusb.3 libusb_get_device_address.3
 MLINKS += libusb.3 libusb_get_device_speed.3
 MLINKS += libusb.3 libusb_get_max_packet_size.3
+MLINKS += libusb.3 libusb_get_max_iso_packet_size.3
 MLINKS += libusb.3 libusb_ref_device.3
 MLINKS += libusb.3 libusb_unref_device.3
 MLINKS += libusb.3 libusb_open.3
diff --git a/lib/libusb/libusb.3 b/lib/libusb/libusb.3
index 24983351881f..a5bf677a66e2 100644
--- a/lib/libusb/libusb.3
+++ b/lib/libusb/libusb.3
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 25, 2012
+.Dd April 12, 2012
 .Dt LIBUSB 3
 .Os
 .Sh NAME
@@ -118,6 +118,12 @@ LIBUSB_SPEED_UNKNOWN is returned in case of unknown wire speed.
 Returns the wMaxPacketSize value on success, LIBUSB_ERROR_NOT_FOUND if the
 endpoint does not exist and LIBUSB_ERROR_OTHERS on other failure.
 .Pp
+.Ft int
+.Fn libusb_get_max_iso_packet_size "libusb_device *dev" "unsigned char endpoint"
+Returns the packet size multiplied by the packet multiplier on success,
+LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist and
+LIBUSB_ERROR_OTHERS on other failure.
+.Pp
 .Ft libusb_device *
 .Fn libusb_ref_device "libusb_device *dev"
 Increment the reference counter of the device
diff --git a/lib/libusb/libusb.h b/lib/libusb/libusb.h
index 5a4d2df98057..5f821b613586 100644
--- a/lib/libusb/libusb.h
+++ b/lib/libusb/libusb.h
@@ -371,6 +371,7 @@ uint8_t	libusb_get_device_address(libusb_device * dev);
 enum libusb_speed libusb_get_device_speed(libusb_device * dev);
 int	libusb_clear_halt(libusb_device_handle *devh, uint8_t endpoint);
 int	libusb_get_max_packet_size(libusb_device * dev, uint8_t endpoint);
+int	libusb_get_max_iso_packet_size(libusb_device * dev, uint8_t endpoint);
 libusb_device *libusb_ref_device(libusb_device * dev);
 void	libusb_unref_device(libusb_device * dev);
 int	libusb_open(libusb_device * dev, libusb_device_handle ** devh);
diff --git a/lib/libusb/libusb10.c b/lib/libusb/libusb10.c
index 0be318a10381..02ad315da6c4 100644
--- a/lib/libusb/libusb10.c
+++ b/lib/libusb/libusb10.c
@@ -331,6 +331,30 @@ libusb_get_max_packet_size(libusb_device *dev, uint8_t endpoint)
 	return (ret);
 }
 
+int
+libusb_get_max_iso_packet_size(libusb_device *dev, uint8_t endpoint)
+{
+	int multiplier;
+	int ret;
+
+	ret = libusb_get_max_packet_size(dev, endpoint);
+
+	switch (libusb20_dev_get_speed(dev->os_priv)) {
+	case LIBUSB20_SPEED_LOW:
+	case LIBUSB20_SPEED_FULL:
+		break;
+	default:
+		if (ret > -1) {
+			multiplier = (1 + ((ret >> 11) & 3));
+			if (multiplier > 3)
+				multiplier = 3;
+			ret = (ret & 0x7FF) * multiplier;
+		}
+		break;
+	}
+	return (ret);
+}
+
 libusb_device *
 libusb_ref_device(libusb_device *dev)
 {