My coworker (who is very clever, but with severly limited inter-personal skills), keeps refactoring my code even when it is work in progress and assigned to me as a task. Whereas I fully subscribed to the idea of collective ownership of code, I find this extremely irritating, but attempts to have him stop seem to have no effect. My analysis of his personality is that he considers himself the best, and if it had not been for him, the codebase would have been in a mess. I should add that I am not a novice, I know my skills and I produce quality work. Some of the refactorings are indeed to the better, most are basically just introduction of a style that he likes better than mine. In addition, he has a almost child-like need to have the last word in any discussion and has never any word of praise for work done by co-workers. There is always something that he, the master, would have done differently. I feel this is strongly affecting the quality of my work-life. What should I do ?