Creating design models that represent usability aspects can promote a better quality in use. However, it is necessary to investigate how do design processes commonly used in industry can be adapted to include this practice. This paper reports a case study in an agile software development company which adopts the Scrum methodology. The company decided to include the usability modeling practice in order to improve the quality of their products. For modeling usability aspects, the company adopted the USINN model in the initial sprints of a web development project. The results indicated that it was possible to integrate usability modeling before starting the development activities, anticipating the concern with usability. The USINN model enabled to prevent usability problems in the UIs developed later and to identify requirements for the application. Moreover, the USINN model was used in the sprint planning.