diff --git a/tool/rand.cc b/tool/rand.cc
index 3701748..b442e0d 100644
--- a/tool/rand.cc
+++ b/tool/rand.cc
@@ -16,6 +16,7 @@
 #include <vector>
 
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
 
 #include <openssl/rand.h>