Digital libraries are important resources for the education of all, including people with disabilities. Designing their interfaces to include broader range of users has been a challenge, partly because to evaluate their accessibility, access to participants is a difficult part. Hence, to overcome such limitation, researchers often use heuristics to evaluate library interfaces. Generic heuristics are typically lengthy or too general, hence not suitable to uncover accessibility issues with library interfaces. In this paper, we address this issue by proposing heuristics specifically designed for the evaluation of digital library interfaces. The initial set of heuristics was derived from four different sources independently rated by two domain experts. In addition, four new items were proposed based on observations we conducted in another study on the accessibility of digital libraries. The final set of heuristics proposed is consisted of sixteen items tailored specifically to evaluate the accessibility of digital library interfaces.