diff --git a/ecdh.c b/ecdh.c
index e2cc5d3..852fed8 100644
--- a/ecdh.c
+++ b/ecdh.c
@@ -36,6 +36,7 @@
     https://www.ietf.org/rfc/rfc4492.txt 
 */
 
+#include <stdio.h>
 #include <stdint.h>
 #include "ecdh.h"