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>
 
diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index de0d108..7663e36 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -33,6 +33,7 @@
 #if defined(MBEDTLS_SSL_COOKIE_C)
 
 #include "mbedtls/ssl_cookie.h"
+#include "mbedtls/ssl_internal.h"
 
 #if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 00e590e..08f228b 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -30,6 +30,7 @@
 
 #include "mbedtls/debug.h"
 #include "mbedtls/ssl.h"
+#include "mbedtls/ssl_internal.h"
 
 #include <string.h>
 
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>