A protection circuit can be used with a computer system having a master device and at least one slave device that are connected by an inter-integrated circuit (I2C) bus. A first access request is received that includes an address that identifies a first slave device. In response to a permissible mode, the first access request is communicated to the first slave device using the I2C bus. A sticky protection bit can be set. In response to the sticky protection bit being set, the protection circuit can be placed in a protected mode. A second access request is received. The second access request can be determined to be a protected access to the first slave device. In response to the determining and the protected mode, the second access request to the first slave device can be denied.