Move a bar?

OK, this is probably an idiotic question that has been answered a zillion times, but obviously I fail at google search. I have a lone bar sticking out at the end of a piece. How do I move it to the previous system?

Engrave mode. Select the first note of the previous system and Cmd/Ctrl-click the last note of the piece; then click the “Make into System” button in the left panel.