During the First World War, the building was closed off on the Dutch side with barbed wire. At the end of the 1930s, the border crossing was locked again by order of the German authorities, this time with iron posts.

When the German troops invaded the Netherlands on 10 May 1940, the barrier was removed and replaced by a movable barbed-wire fence. Today, Kleng Wach is the smallest museum in Vaals.