We examine whether firms increase their employment of R&D personnel in response to an expansion of tertiary education institutions, i.e., a supply shock of skilled labor. We use the staggered introduction of Universities of Applied Sciences (UASs) in Switzerland as a quasi-natural experiment to identify causal effects. Firms located near a new UAS campus experience an education-driven labor supply shock in the form of UAS graduates newly entering the local labor market. Using a large representative firm survey and applying a difference-in-differences model, we find that this labor supply shock has positive effects: first, on the percentage of R&D personnel relative to total employment and, second, on the percentage of total wages paid to them. These effects are driven by both very small firms (five to nine employees) and very large ones (5,000 or more). Our findings suggest that a tertiary education expansion can stimulate innovation activities by increasing the personnel resources devoted to R&D.