An improved explicit estimate for $\zeta (1\mathrm{/}2+it)$

An explicit subconvex bound for the Riemann zeta function $\zeta (s)$ on the critical line $s=1\mathrm{/}2+it$ is proved. Previous subconvex bounds relied on an incorrect version of the Kusmin-Landau lemma. After accounting for the needed correction in that lemma, we recover and improve the record explicit bound for $\mathrm{\mid }\zeta (1\mathrm{/}2+it)\mathrm{\mid }$.