  Let A and B be subsets of an elementary abelian 2-group G, none of which are
contained in a coset of a proper subgroup. Extending onto potentially distinct
summands a result of Hennecart and Plagne, we show that if |A+B|<|A|+|B|, then
either A+B=G, or the complement of A+B in G is contained in a coset of a
subgroup of index at least 8, whence |A+B| is at least 7/8 |G|. We indicate
conditions for the containment to be strict, and establish a refinement in the
case where the sizes of A and B differ significantly.
