Cheating is a common human behavior but few studies have examined its emergence during early childhood. In three preregistered studies, a challenging math test was administered to 5- to 6-year-old children (total N = 500; 255 girls). An answer key was present as children completed the test, but they were instructed to not peek at it. In Study 1, many children cheated, but manipulations that reduced the answer key's accessibility in terms of proximity and visibility led to less cheating. Two follow-up studies showed that the answer key's visibility played a more significant role than its proximity. These findings suggest that subtle and seemingly insignificant alterations of the physical environment can effectively nudge young children away from acting dishonestly.