Through providing a virtual environment modeled from embedded devices, firmware rehosting enables dynamic analysis on embedded device firmware. Existing full-emulation firmware hosting solutions can only preventatively fix known hardware and software dependencies but cannot address undetected dependencies during the rehosting process. This study proposes FirmDep, an embedded application rehosting solution assisted with dynamic analysis. During the rehosting process, FirmDep records the execution trace and system state of the embedded application to be analyzed. If FirmDep fails to rehost the application, FirmDep extracts information and recover system states from the execution trace, then uses several algorithms to identify and arbitrate the unresolved dependency problems. The prototype system of FirmDep is implemented based on PANDA and angr, and it is tested with embedded Web applications from 217 real-world firmware images. The results show that FirmDep can effectively identify unresolved dependencies of embedded application and improve the success rate of rehosting.