diff --git a/gtk2_ardour/plugin_selector.h b/gtk2_ardour/plugin_selector.h
index 9a71d28780..8c76965384 100644
--- a/gtk2_ardour/plugin_selector.h
+++ b/gtk2_ardour/plugin_selector.h
@@ -29,6 +29,8 @@
 #include "ardour/session_handle.h"
 #include "plugin_interest.h"
 
+#include "ardour_dialog.h"
+
 namespace ARDOUR {
 	class Session;
 	class PluginManager;