diff --git a/libs/ardour/sndfile_helpers.cc b/libs/ardour/sndfile_helpers.cc
index 6f5039b430..84e97152e9 100644
--- a/libs/ardour/sndfile_helpers.cc
+++ b/libs/ardour/sndfile_helpers.cc
@@ -18,6 +18,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include <string>
 #include <sndfile.h>
 #include "ardour/sndfile_helpers.h"