--- freedesktop.org.xml.in
+++ freedesktop.org.xml.in
@@ -3022,6 +3022,7 @@
     </magic>
   </mime-type>
   <mime-type type="video/x-ms-wmv">
+    <sub-class-of type="video/x-ms-asf"/>
     <_comment>WMV video</_comment>
     <acronym>WMV</acronym>
     <expanded-acronym>Windows Media Video</expanded-acronym>