We present two novel derivations of the recently established (-)(p) factor in the charge quantization condition for p-brane dyon sources in spacetime dimension D = 2p + 2. The first requires consistency of the condition under the charge shifts produced by(generalized) theta-terms. The second traces the sign difference between adjoining dimensions to compactification effects. (C) 1998 Published by Elsevier Science B.V. All rights reserved.