Hi, I just pushed an even simpler test case that shows the "defect": https://github.com/lelit/buildout/commit/1dc3d6af0b6326500ad72798352dd153736... that hopefully will help spotting the bug (or maybe my bad usage of the extends functionality :-) I already tried to tweak the _update_section() function, but without success: AFAIU, with the test above at some point the destination section (`s1` in the function) contains *both* a "egg" and a "egg +" keys, so the line # Find v1 in s2 first; it may have been defined locally too. v1, note1 = s2.get(key, s1.get(key, ("", ""))) where `key` is "egg" ignores the s1['egg +'] value... I'll try to spend some more hours on it. Thanks and bye, lele. -- nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia. lele@metapensiero.it | -- Fortunato Depero, 1929.