diff --git a/content/pages/space.xml b/content/pages/space.xml
index 3995846eb..bd5a03715 100644
--- a/content/pages/space.xml
+++ b/content/pages/space.xml
@@ -48,7 +48,7 @@
     <!-- <div itemprop="alternateName">&lt;&lt;&lt;/&gt;&gt; c3d2 &lt;&lt;&lt;/&gt;&gt;</div> -->
     <span itemprop="name" class="org">Netzbiotop e.V.</span> / <span class="fn">Chaos Computer Club Dresden</span>
     <div itemprop="address" itemscope="itemscope" itemtype="http://schema.org/PostalAddress" class="adr address">
-      Briefkasten <span class="post-office-box">75</span>,
+      Briefkasten <span itemprop="postOfficeBoxNumber" class="post-office-box">75</span>,
       <span class="extended-address">robotron-Bürokomplex</span>,
       <span itemprop="streetAddress" class="street-address">Lingnerallee 3</span>,
       <span itemprop="postalCode" class="postal-code">01069</span>