  IIB compactifications enjoy the possibility to break GUT groups via fluxes
without giving mass to the hypercharge gauge field. Although this important
advantage has greatly motivated F-theory constructions, no such fluxes have
been constructed directly in terms of the M-theory $G_4$-form. In this note, we
give a general prescription for constructing hypercharge G-fluxes. By using a
stable version of Sen's weak coupling limit, we verify their connection with
IIB fluxes. We illustrate the lift of fluxes in a number of examples, including
a compact ${\rm SU}(5) \times {\rm U}(1)$ model with explicit realization of
doublet-triplet splitting. Finally, we prove an equivalence conjectured in an
earlier work as a by-product.
