  We show that two blocks of generalized quaternion defect with three simple
modules over a sufficiently large $2$-adic ring $\mathcal O$ are
Morita-equivalent if and only if the corresponding blocks over the residue
field of $\mathcal O$ are Morita-equivalent. As a corollary we show that any
two blocks defined over $\mathcal O$ with three simple modules and the same
generalized quaternion defect group are derived equivalent.
