Arduino-OWI with AtTinyCore

So I'm able to build the "examples/Slave/Arduino.ino" (a general onewire slave device) for Arduino Uno just fine.
However my real target is ATtinyx5 when I switch the board to ATtiny25/45/85 I get


pins_arduino.h: 45:14: error: expected identifier before numeric constant
   #define SS   3
Board.h:425: note  in expansion of macro SS
   SS = D3,   \\!< SPI Slave Select
 
pins_arduino.h: 45:14: error: expected '}' before numeric constant
   #define SS   3
Board.h:425: note  in expansion of macro SS
   SS = D3,   \\!< SPI Slave Select
 
pins_arduino.h: 45:14: error: expected unqualified-id before numeric constant
   #define SS   3
Board.h:425: note  in expansion of macro SS
   SS = D3,   \\!< SPI Slave Select
 
GPIO.h:22: In file included from
GPIO.h:22: from
Arduino.ino:1: from
 
Board.h: 430:1: error: expected declaration before '}' token

Where pins_arduino.h is part of ATTinyCore and Board.h is in the Arduino-OWI dependency Arduino-GPIO.
It seems that the symbols SS, MISO, MOSI, SCK are multiply defined.
How to resolve this?