diff --git a/simgear/structure/subsystem_mgr.hxx b/simgear/structure/subsystem_mgr.hxx
index c49d73fd..0de20ef8 100644
--- a/simgear/structure/subsystem_mgr.hxx
+++ b/simgear/structure/subsystem_mgr.hxx
@@ -29,8 +29,8 @@
 #include <map>
 #include <vector>
 
-#include <simgear/props/props.hxx>
 #include <simgear/timing/timestamp.hxx>
+#include <simgear/structure/SGSharedPtr.hxx>
 #include "SGSmplstat.hxx"