diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp b/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp
index da47395701..25dbec3fec 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp
@@ -97,9 +97,9 @@ AP_OpticalFlow::update_position(float roll, float pitch, float cos_yaw_x, float
 		x_cm = -change_x * avg_altitude * conv_factor;    // perhaps this altitude should actually be the distance to the ground?  i.e. if we are very rolled over it should be longer?
 		y_cm = -change_y * avg_altitude * conv_factor;    // for example if you are leaned over at 45 deg the ground will appear farther away and motion from opt flow sensor will be less
 
-
-		vlon =  x_cm * sin_yaw_y - y_cm * cos_yaw_x;
-		vlat =  y_cm * sin_yaw_y - x_cm * cos_yaw_x;
+		// convert x/y movements into lon/lat movement
+		vlon = x_cm * sin_yaw_y + y_cm * cos_yaw_x;
+		vlat = y_cm * sin_yaw_y - x_cm * cos_yaw_x;
 	}
 
 	_last_altitude = altitude;
diff --git a/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.pde b/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.pde
index 057e9d5353..ef8c604a2c 100644
--- a/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.pde
+++ b/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.pde
@@ -3,10 +3,23 @@
   Code by Randy Mackay. DIYDrones.com
 */
 
+#include <FastSerial.h>
+#include <AP_Common.h>
 #include <AP_Math.h>		// ArduPilot Mega Vector/Matrix math Library
-#include <SPI.h>      // Arduino SPI library
+#include <SPI.h>      		// Arduino SPI library
+#include <AP_DCM.h>			// ArduCopter DCM Library
 #include "AP_OpticalFlow.h" // ArduCopter OpticalFlow Library
 
+////////////////////////////////////////////////////////////////////////////////
+// Serial ports
+////////////////////////////////////////////////////////////////////////////////
+//
+// Note that FastSerial port buffers are allocated at ::begin time,
+// so there is not much of a penalty to defining ports that we don't
+// use.
+//
+FastSerialPort0(Serial);        // FTDI/console
+
 AP_OpticalFlow_ADNS3080 flowSensor;
 
 void setup()
@@ -297,7 +310,7 @@ void display_motion()
 	
 	while( !Serial.available() ) {
 	    flowSensor.read();
-		flowSensor.get_position(0,0,0,100);
+		flowSensor.update_position(0,0,0,1,100);
 
 		// x,y,squal
 		//if( flowSensor.motion() || first_time ) {