This paper presents an enhanced approach for adapting a Language Model (LM) to a specific domain, with a focus on Named Entity Recognition (NER) and Named Entity Linking (NEL) tasks. Traditional NER/NEL methods require a large amounts of labeled data, which is time and resource intensive to produce. Unsupervised and semi-supervised approaches overcome this limitation but suffer from a lower quality. Our approach, called KeyWord Masking (KWM), fine-tunes a Language Model (LM) for the Masked Language Modeling (MLM) task in a special way. Our experiments demonstrate that KWM outperforms traditional methods in restoring domain-specific entities. This work is a preliminary step towards developing a more sophisticated NER/NEL system for domain-specific data.