This paper presents the development of a multimodal warning display for a paper mill control room. In previous work, an informative auditory display for control room warnings was proposed. The proposed auditory solution conveys information about urgent events by using a combination of auditory icons and tonal components. The main aim of the present study was to investigate if a complementary visual display could increase the effectiveness and acceptance of the existing auditory solution. The visual display was designed in a user-driven design process with operators. An evaluation was conducted both before and after the implementation. Subjective ratings showed that operators found it easier to identify the alarming section using the multimodal display. These results can be useful for any designer intending to implement a multimodal display for warnings in an industrial context. © 2017 Copyright is held by the owner/author(s).