A computing device receives one or more indications of user input to enter a character string. In response, the computing device determines, based on a corpus that includes punctuated character strings previously entered by a user of the computing device, one or more punctuated versions of the character string. Each of the one or more punctuated versions of the character string includes one or more punctuation marks not present in the character string. The computing device outputs, for display, at least one of the one or more punctuated versions of the character string.