A wireless device has at least first and second radio systems. A first of the radio systems provides an indication for a second of the radio systems that it is transmitting or is about to transmit. The actual interference caused by transmissions by the first radio system to operation of the second radio system is measured, and/or the likely interference caused by transmissions by the first radio system to operation of the second radio system is estimated. The behavior of at least one of the first and second radio systems is modified in order to reduce the interference depending on the measured actual interference or estimated likely interference.