(Psalm 4:2) cum invocarem exaudivit me Deus iustitiae meae in tribulatione dilatasti mihi miserere mei et exaudi orationem meam
When I called upon him, the God of my justice heard me: when I was in distress, thou hast enlarged me. Have mercy on me: and hear my prayer.
From the context of the above Psalm verse, dilatasti seems to be 2nd-person singular perfect active indicative. Moreover, that is the parsing information given by this site.
However, my Latin dictionary lists dilatavi as the third principal part, which means dilatavi is the 1st-person singular perfect active indicative. Therefore, it seems that dilatavisti would be the 2nd-person singular perfect active indicative. Moreover, Wiktionary lists dilatavisti as the 2nd-person singular perfect active indicative.
Which is the correct form?