diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc
index 311f962471..a1c7c67d2b 100644
--- a/libs/ardour/interpolation.cc
+++ b/libs/ardour/interpolation.cc
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include <cstdio>
 
 #include "ardour/interpolation.h"