Proto-Slavic *jako

→ Belarusian як (inherited)

→ Belarusian як (inherited(be/uk))

→ Bulgarian ако (inherited)

→ Czech jak (inherited)

→ Czech jako (inherited)

→ Kashubian jak (inherited)

→ Old Church Slavonic ꙗко (inherited)

→ Macedonian ако (inherited)

→ Polish jak (inherited)

→ Polish jako (inherited)

→ Russian яко (inherited)

→ Serbo-Croatian ako (inherited)

→ Serbo-Croatian jako (inherited)

→ Serbo-Croatian ако (inherited)

→ Slovak ako (inherited)