It seems that there is an issue when calling callNextMethod() inside a method without "..." in its formals but defined on a generic WITH "..." in its formals. Whenever that method is called with an argument that is not explicitly named in the generic formals, we get the following error: setClass("A") setClass("B", contains = "A") setGeneric("fun", function(x, ...) standardGeneric("fun")) setMethod("fun", "A", function(x, y) x) setMethod("fun", "B", function(x, y) callNextMethod()) fun(new("B"), "foo") Error in callNextMethod() : in processing 'callNextMethod', found a '...' in the matched call, but no corresponding '...' argument Is this a misuse of callNextMethod? Thanks, Michael [[alternative HTML version deleted]]