Let $X$ be an $n$-dimensional proper algebraic variety over $K$, $\overline{L}=(L,\|\cdot\|)$ a formally metrized line bundle on $X^{\textup{an}}$ and $\tau$ an open face of dimension $n$ of a skeleton corresponding to a strictly semistable formal model $\mathfrak{X}$ of $X^{\textup{an}}$ on which $\overline{L}$ has a formal model $\mathfrak{L}$. Let $\varphi$ be a continuous function on $X^{\textup{an}}$ such that $\|\cdot\|e^{-\varphi}$ is a semipositive metric. Suppose that $\varphi$ factorizes through the retraction $p_{\mathfrak{X}}$ onto the skeleton. Then

$$c_{1}(L,\|\cdot\|e^{-\varphi})^{n}=[\tilde{K}(S):\tilde{K}]\cdot n!\cdot\MA\left(\varphi\Big|_{\tau}\right)$$

on $p_{\mathfrak{X}}^{-1}(\tau)$ where $\MA$ denotes the real Monge-Ampère operator on $\tau$ which is considered to be a measure on $p_{\mathfrak{X}}^{-1}(\tau)$ by pushforward via the inclusion and $S$ denotes the point in the special fibre of $\mathfrak{X}$ which is the image of $\tau$ under the reduction map.