Cherry Nut Pie

1 can (20 ounces) pitted sour red cherries
1 pkg. (3 ounces) cherry flavor gelatin
1/8 tsp. cinnamon
1 cup sugar
1 cup boiling water
1/2 cup chopped nuts
1 baked 9-inch pie shell, cooled

Drain cherries, measuring juice. If necessary, add water to juice to equal 3/4 cup. Combine gelatin and cinnamon. Add sugar and dissolve in boiling water. Add measured liquid. Chill until thickened. Fold in cherries and nuts. Pour into baked pie shell. Chill until firm. Garnish with prepared whipped topping if desired.