This paper examines the impact of architectural decisions on the level of defects in a product. We view products as collections of components linked together to work as an integrated whole. Previous work has established modularity (how decoupled a component is from other product components) as a critical determinant of defects, and we confirm its importance. Yet our study also provides empirical evidence for a relation between product quality and cyclicality (the extent to which a component depends on itself via other product components). We find cyclicality to be a determinant of quality that is distinct from, and no less important than, modularity. Extending this main result, we show how the cyclicality–quality relation is affected by the centrality of a component in a cycle and the distribution of a cycle across product modules. These findings, which are based on analysis of open source software development projects, have implications for the study and design of complex systems.