There is a paper that was published 15 years ago; one of the theorems in it is wrong in general. A few years ago some people told the author that this theorem is wrong as stated, but yet a partial case of it is true and is quite sufficient for the proof of the main result of the paper. Certainly, it was too late to correct the paper itself; yet its current arXiv version contains a short notice that it should be corrected. Now, I proved a (new) corrected and extended version of the wrong result mentioned. My method of the proof has benefited significantly from the 'wrong proof'. So, what should I do (in order not to offend the authors of the paper mentioned)? I have the following ideas. 1. Avoid citing the 'partially wrong' paper. Actually, my result is not something very much unexpected, and the proof is rather short and easy; I could have found it without reading the 'wrong' paper. 2. Cite the printed version of the paper, and tell the reader that the result mentioned is wrong as stated? In this situation I definitely would like to say that this result is wrong, since if I do not do so, nobody will understand why my correction is interesting. As is often the case, the wrong result looks nicer than the correct one.:) 3. Cite the current arXiv version. The problem is that it contains a notice that a revision is necessary, but no revision is made. 4. Ask the author(s) of the paper to put a corrected version of it to the arXiv. In this situation, is it ok to tell the authors that I do not want to cite the printed version of the paper as well as the current arXiv version? If I choose possibilities 3 and 4, should I explain somehow (in my preprint) why I cite the arXiv version and not the printed one?