diff --git a/libs/pbd/xml++.cc b/libs/pbd/xml++.cc
index 7c6fffe7f8..3046f971ab 100644
--- a/libs/pbd/xml++.cc
+++ b/libs/pbd/xml++.cc
@@ -5,6 +5,7 @@
  * Modified for Ardour and released under the same terms.
  */
 
+#include <iostream>
 #include "pbd/xml++.h"
 #include <libxml/debugXML.h>
 #include <libxml/xpath.h>