diff --git a/libs/ardour/vst_plugin.cc b/libs/ardour/vst_plugin.cc
index 505a49360f..cf083e87f1 100644
--- a/libs/ardour/vst_plugin.cc
+++ b/libs/ardour/vst_plugin.cc
@@ -22,6 +22,7 @@
 
 #include <glibmm/fileutils.h>
 #include <glibmm/miscutils.h>
+#include <glibmm/convert.h>
 
 #include "pbd/floating.h"
 #include "pbd/locale_guard.h"