diff --git a/src/simple-tone-generator.c b/src/simple-tone-generator.c
index 4971786..80bc108 100644
--- a/src/simple-tone-generator.c
+++ b/src/simple-tone-generator.c
@@ -22,6 +22,7 @@
 #include <strings.h>
 #include <stdlib.h>
 #include <assert.h>
+#include <stdio.h>
 
 #include "simpleaudio.h"