Hi, I just discovered a funny thing. If you create a Set with Set new, you will get a Set with an internal array of 5 elements (hardcoded in Set class>>#new). If you ask explicitly a Set for one or no element: Set new: 0 (or a number between 0 and 5), you will get an internal array of 7 elements. This behavior is a bit strange. Either we always need at least 7 elements and we need to update Set class>>#new, either the method Set class>>#sizeFor: should be updated.