A heat exchanger includes first and second sets of parallel arranged tubes. The first set of tubes extends along a first arcuate path, the second set of tubes extends along a second arcuate path, and each one of the second set of tubes is aligned in a common plane with a corresponding one of the first set of tubes. Corrugated fin segments are arranged in spaces between adjacent tubes, and crests and troughs of the corrugated fin segments are joined to broad and flat faces of the tubes. In making the heat exchanger, the material of the corrugated fin segment is intermittently slit to define breaking points prior to arranging the corrugated fin segment between the tubes.