In-store mobile shopping apps can reduce queues in supermarkets and improve the consumer's shopping experience, yet their usage rates remain low. Despite the advances in mobile commerce literature, only scant research discusses the design inhibitors of in-store mobile shopping apps. This paper uses the Theory of Technology Usage Inhibitors to investigate inhibitors in designing in-store mobile shopping apps. We adopt a topic modelling approach to analyse 1800 Apple store reviews to identify the most significant inhibitors in a UK supermarket in-store mobile shopping app. Our findings identify redundancy, malfunctioning, overcharging, fiddliness, poor support, difficulty registering and objecting benefits as the critical design inhibitors. Our study expands the theory of technology usage inhibitors (Cenfetelli 2004) in the context of in-store shopping apps by identifying and conceptualising design-based inhibitors that discourage use. This paper contributes important design insights and recommendations to support app designers and retailers in effectively designing in-store shopping apps.