We introduce WikiDoMiner -- a tool for automatically generating domain-specific corpora by crawling Wikipedia. WikiDoMiner helps requirements engineers acquire an external knowledge resource that is specific to the underlying domain of a given requirements specification (RS). Having the possibility to build a such a corpus is important since domain-specific datasets are scarce. WikiDoMiner generates the corpus by first extracting a set of domain-specific keywords from the RS, and then querying Wikipedia for these keywords. The output of WikiDoMiner is a set of Wikipedia articles that are relevant to the domain of the input RS. Mining Wikipedia for domain-specific knowledge can be beneficial for multiple requirements engineering essential tasks, e.g., ambiguity handling, consistency checking, and question answering.