  Consider the set $\uu$ of real numbers $q \ge 1$ for which only one sequence
$(c_i)$ of integers $0 \le c_i \le q$ satisfies the equality
$\sum_{i=1}^{\infty} c_i q^{-i} = 1$. In this note we show that the set of
algebraic numbers in $\uu$ is dense in the closure $\uuu$ of $\uu$.
