@@ -219,7 +219,7 @@ class Converter:
else:
letter = self._matched_letters[letter]
- buffer += (letter.capitalize() if letter[0] == 'j' else letter.upper()) if self._is_upper(n) else letter
+ buffer += (letter.capitalize() if letter and letter[0] == 'j' else letter.upper()) if self._is_upper(n) else letter
self._output += buffer
