Wireless LANs (WLAN) are becoming ubiquitous, as more and more consumer electronic equipments start to support them. This creates new security concerns, since hackers no longer need physical connection to the networks linking the devices, but only need to be in their proximity, to send malicious data to exploit some vulnerability. In this paper we present a fuzzer, called Wdev-Fuzzer, which can be utilized to locate security vulnerabilities in Wi-Fi device drivers. Our experiments with a Windows Mobile 5 device indicate that Wdev-Fuzzer can be quite effective in confirming known issues and discovering previously unknown problems.