Informal observation suggests that it is harder to notice the spelling mistake in "silencne" than "silencre." This concurs with current evidence that non-adjacent letter repetition in correctly spelled words makes these words harder to recognize. One possible explanation is provided by open-bigram coding. Words containing repeated letters are harder to recognize because they are represented by fewer bigrams than words without repeated letters. Building on this particular explanation for letter-repetition effects in words, we predicted that nonwords in a lexical decision task should also be sensitive to letter repetitions. In particular, we examined two types of nonwords generated from the same baseword: (1) nonwords created by repeating one of the letters in the baseword (e.g., silence => silencne); and (2) nonwords created by inserting a letter that is not present in the baseword (e.g., silencre). According to open-bigram coding, nonwords created by repeating a letter are more similar to their baseword than nonwords created by inserting a letter, and this should make it harder to reject letter repetition nonwords than letter insertion nonwords. We put these predictions to test in one on-line pilot study (n=31), one laboratory experiment (n=36), and one followup on-line experiment (n=40) where we manipulated the distance between repetitions (one, two, three, or four letters). Participants found it harder to reject repetition nonwords than insertion nonwords, and this effect diminished with increasing distance.