diff --git a/src/gui/auxiliary/iterator/policy_order.hpp b/src/gui/auxiliary/iterator/policy_order.hpp
index e56bc63dacb4..1a926a41f3c6 100644
--- a/src/gui/auxiliary/iterator/policy_order.hpp
+++ b/src/gui/auxiliary/iterator/policy_order.hpp
@@ -16,6 +16,7 @@
 
 #include "gui/auxiliary/iterator/exception.hpp"
 #include "gui/auxiliary/iterator/policy_visit.hpp"
+#include "gui/auxiliary/iterator/walker.hpp"
 #include "gui/core/log.hpp"
 #include "gui/widgets/widget.hpp"