This challenge presents hazardous conditions for common Wireless Sensor Network (WSN) MAC protocols to operate in. ContikiMAC uses Clear Channel Assessments (CCA) for transmitting and receiving packets. Since CCA checks only measure the channel energy, nodes cannot differentiate a ContikiMAC sender from other interference. Coupled with the design of ContikiMAC, this ambiguity causes reduced energy efficiency, and link performance, in busy environments. Here, we propose an extension to ContikiMAC to prevent f alse wakeups, which are the result of ambiguous CCA results. By implementing a Differentiating CCA (DCCA), which can tell apart ContikiMAC packets from other interference, false wakeups are prevented. As well, specific responses to sources of interference can be made following a channel collision, thereby potentially achieving better link performance.