Attiny85 and Manchester.h

Working on a project where i need to transmitt wirelessly from a Nano to an Attiny85.
Tried with IR, but it's a bit on and off whether it gets the signal. So i wanted to try with RF instead.
Got my correct tiny cores from google codes. Got the right library from Manchester.h.
Seems good. But one line in my code, make the attiny85 go crazy. Like it speeds up the clock.

In my main loop i set my nano to turn led on, delay(300), turn off, then delay again.
Did the same on the tiny, and it blinked in a nice pace. Correctly.

BUT when i add this line to the tiny: man.setupReceive(rec_pin, MAN_1200);

It speeds up and blinks 2-3 times as fast as the nano.

Anyone know why?
The higher number after MAN_, the faster. Lower number: slower.

You're using a Tiny85 core that uses timer1 for timekeeping, but that manchester library tries to take over that timer, assuming that millis is on timer0.

Use a different core, or modify the library.

Tried different cores, but then i get compilation errors. I see in manchester.cpp that it uses Timer1.

Got any more tips?