diff --git a/libs/ardour/session_butler.cc b/libs/ardour/session_butler.cc
index 53fa929ff7..a682eff599 100644
--- a/libs/ardour/session_butler.cc
+++ b/libs/ardour/session_butler.cc
@@ -29,6 +29,7 @@
 #include "ardour/route.h"
 #include "ardour/session.h"
 #include "ardour/session_event.h"
+#include "ardour/session_route.h"
 #include "ardour/track.h"
 #include "ardour/types.h"