This paper presents a method for optimizing software updates of consumer electronic devices running multiple applications with a common software component, called horizontal patching. Instead of using separate deltas for patching different applications, the method generates one delta from the other. Due to the large similarities between the deltas, this horizontal delta is small in size. Experimental results on two test sets, consisting of software updates for sensor networks and smart phones, show that significant improvements can be achieved. Between 27% and 84% data can be saved from transmission, depending on the type of applications and shared components.