diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 79d1b93..f22c561 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -38,6 +38,7 @@
 
 #include "mbedtls/debug.h"
 #include "mbedtls/ssl.h"
+#include "mbedtls/ssl_internal.h"
 
 #include <string.h>