diff --git a/gtk2_ardour/template_dialog.cc b/gtk2_ardour/template_dialog.cc
index 53277e62aa..4b2813b7d5 100644
--- a/gtk2_ardour/template_dialog.cc
+++ b/gtk2_ardour/template_dialog.cc
@@ -19,6 +19,7 @@
 */
 
 #include <map>
+#include <cerrno>
 
 #include <glib/gstdio.h>