diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index f344907..b935f59 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -30,6 +30,7 @@
 
 #include "mbedtls/debug.h"
 #include "mbedtls/ssl.h"
+#include "mbedtls/ssl_internal.h"
 
 #include <string.h>