In weight-sensitive languages, stress is influenced by syllable weight. As a result, heavy syllables should attract, not repel, stress. The Portuguese lexicon, however, presents a case where weight seems to negatively impact stress: antepenultimate stress is more frequent in light antepenultimate syllables than in heavy ones. This pattern is phonologically unexpected and appears to contradict the typology of weight and stress: it is a case where lexical statistics and the grammar conflict. Portuguese also contains gradient, not categorical, weight effects, which weaken as we move away from the right edge of the word. In this article, I examine how native speakers’ grammars capture these subtle weight effects, and whether the negative antepenultimate weight effect is learned or repaired. I show that speakers learn the gradient weight effects in the language, but do not learn the unnatural negative effect. Instead, speakers repair this pattern and generalize a positive weight effect to all syllables in the stress domain. This study thus provides empirical evidence that speakers may not only ignore unnatural patterns, but also learn the opposite pattern.