Miter each corner so no raw fabric is exposed at the edges of the patch. (See the next step for video instructions.)

Unfold the seam allowance on either side of the corner.

Use the fold lines to determine the diagonal line that bisects the point where the folds intersect.

Fold the corner inward along this diagonal line.

Refold the seam allowances of the adjacent patch sides. If done correctly, their corner edges will meet at a 45-degree angle.

Press the fabric in place and repeat on each corner.