diff --git a/intra.cpp b/intra.cpp
index ba6d6abe..9c5c7f61 100644
--- a/intra.cpp
+++ b/intra.cpp
@@ -833,6 +833,8 @@ EX void show_portals() {
     }
   else dialog::addBreak(100);
 
+  dialog::addBoolItem_action(XLAT("build on walls"), mapeditor::building_mode, 'B');
+
   walking::add_options();
 
   dialog::addHelp();