diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 55be047..923f2b5 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -41,6 +41,7 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/version.h"
 #include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <string.h>