Aspergillus fumigatus is a human opportunistic pathogen that can cause life-threatening disease in immunocompromised individuals. Treatment with antifungal drugs is often unsuccessful owing to the emergence of resistance. Cell-to-cell heterogeneity has been linked to drug susceptibility and thus might affect drug treatment. Bleichrodt et al. investigated the composition of cell walls of single fungal conidia cells and how this might affect drug susceptibility. They found that the fungal cell wall is highly heterogeneous and that the level of heterogeneity changed during germination and under different conditions. Investigating whether this heterogeneity has an effect on single cell behaviour, the authors showed that subpopulations of germinating conidia emerged that developed tolerance to a cell wall synthesis-targeting antifungal. Thus, cell wall heterogeneity provides a fitness benefit to A. fumigatus.