diff --git a/test_tls.c b/test_tls.c
index d137602..d2cdd9c 100644
--- a/test_tls.c
+++ b/test_tls.c
@@ -65,6 +65,10 @@ struct certkey {
 /* How much K to transfer between client and server. */
 #define KTRANSFER (1 * 1024)
 
+static void err(const int i, const char* msg)
+{
+   printf(msg);
+}
 /*
  * Simple TLS Server code is based on
  * https://wiki.openssl.org/index.php/Simple_TLS_Server