I2C addresses > 63 are not usable with atTiny85

Question

Hi I have a big problem with addressing multiple attiny85-chips with I2C:

For what I know the attiny uses 7-bit addresses for communication. I am using the TinyWireS lib, which works perfectly fine for me, untill I am reaching address: '64' which is '1000000' in binary. The highest usable address should be '1111111'.

This is what happens:

Slave:

Attiny85: switches led on or off when msg is received over I2C.

Slaveaddress: 64

#include <TinyWireS.h>
#include <usiTwiSlave.h>

#define output (4)
#define I2C_SLAVE_ADDR (64) //works if I2C_SLAVE_ADDR < 64

void setup() {
  TinyWireS.begin(I2C_SLAVE_ADDR);
  pinMode(output, OUTPUT);
}

volatile bool state = LOW;

void loop() {
  byte msg = -1;
  if(TinyWireS.available())
    msg = TinyWireS.receive();

  if(msg == 1)
    state = HIGH;
  else if(msg == 0)
    state = LOW;
  else if(msg == 2)
    state = !state;

  digitalWrite(output, state);
}

Master:

Arduino pro mini:

sendMsg(0, true); //works! led on chip: 64 switches on

sendMsg(64, true); //fails! led on chip: 64 is off.

#include <Wire.h>

#define DEVICE (64) //0 works!

void setup() {
    Wire.begin();
}

void loop() {
    sendMsg(1, DEVICE);
    delay(2000);
    sendMsg(0, DEVICE);
    delay(2000);
}

void sendMsg(int msg, int device) {
    Wire.beginTransmission(device);
    Wire.write(msg);
    Wire.endTransmission();
}

Have you any idea how to solve this problem?

TinyWireS version I am using: https://github.com/rambo/TinyWire/tree/master/TinyWireS