Linker error using Mavlink with FastSerial

Hi all,

Has anyone got any experience using MAVlink and therefore FastSerial on Arduino?

I've got an odd linking error, where it's not liking "Serial.begin(57600);".

source071211.cpp.o: In function `setup':
C:\Users\Simon\AppData\Local\Temp\build7399018532809904204.tmp/source071211.cpp:102: undefined reference to `FastSerial::begin(long)'

Any ideas from anyone who's done this before?

MAVlink: http://qgroundcontrol.org/dev/mavlink_arduino_integration_tutorial

FastSerial: http://code.google.com/p/arducam-osd/source/browse/trunk/Library/FastSerial/?r=245