  The aim of this note is to prove that any compact non-trivial almost Ricci
soliton $\big(M^n,\,g,\,X,\,\lambda\big)$ with constant scalar curvature is
isometric to a Euclidean sphere $\Bbb{S}^{n}$. As a consequence we obtain that
every compact non-trivial almost Ricci soliton with constant scalar curvature
is gradient. Moreover, the vector field $X$ decomposes as the sum of a Killing
vector field $Y$ and the gradient of a suitable function.
