diff --git a/libs/ardour/ardour/transport_master.h b/libs/ardour/ardour/transport_master.h
index 9da0378fb1..ecb6f28023 100644
--- a/libs/ardour/ardour/transport_master.h
+++ b/libs/ardour/ardour/transport_master.h
@@ -22,7 +22,6 @@
 
 #include <vector>
 
-#include <boost/atomic.hpp>
 #include <boost/optional.hpp>
 
 #include <glibmm/threads.h>