The composition year of the "Fantasia in D minor" is uncertain, but it is believed to have been composed around 1782. As its title "Fantasia" suggests, the piece is written in a free form, and inspiration is fully displayed, such as in the arpeggiated section that serves as an introductory role at the beginning, and the beautiful, melancholic theme. However, this piece is incomplete, and the final 10 measures of the version currently performed were completed by another hand after Mozart's death. This completion is attributed to the composer and organist August Müller, though the exact details are unknown.