That is the DEFINITION of evolution that one learns in Biology 101. It's no fallacy.
The fallacy comes in when you assume that a DEFINITION can be extrapolated backward into unobservable time.
Remember science? Observable, testable, repeatable? Well, when you extrapolate current observations back into unobservable time based on a DEFINITION, you have engaged in logical fallacy and it is no longer science.
I tried to warn you...