In Proto-Balto-Slavic, short PIE vowels were preserved, with the change of > as in Proto-Germanic. A separate reflex of the original or is, however, argued to have been retained in some environments as a lengthened vowel because of Winter's law. Subsequently, Early Proto-Slavic merged and which were retained in the Baltic languages. Additionally, accentual differences in some Balto-Slavic languages indicate whether the post-PIE long vowel originated from a genuine PIE lengthened grade or is a result of compensatory lengthening before a laryngeal.