In recent years, mobile devices have become one of the main tools for communication and now represent a unique opportunity to reach great numbers of users. Also, Google's Android OS is the one that has grown into a first choice for developing applications. This situation has a diversity of challenges, one of them being ensuring a rich and engaging user experience. One of the most restrictive and unique aspects of mobile development is the diversity in support for screen sizes and/or resolutions. This characteristic can mean different user experiences for users with the same application and has become increasingly important to consider when evaluating usability. In view of this, a proposal was made of an adaptation for the Heuristic Evaluation method, targeting applications that could be used in a range of devices with multiple screen sizes. To validate the proposal, a case study was conducted, evaluating a well-known banking application in Peru, using the proposed adaptation of the method described by Nielsen. This validation consisted of two groups of evaluators, one using traditional Nielsen heuristics, and a second group using context specific heuristics. As a result of the validation, the second group found more issues related with screen size. The proposed adaptation showed positive results, especially if a predefined set of devices, representative of the most common sizes sub-groups is used. As conclusion to the study, the evaluation conducted is an indication that careful consideration should be taken when building applications for a broad range of users, and devices.