diff --git a/programs/ssl/dtls_client.c b/programs/ssl/dtls_client.c
index d3885aa..4052975 100644
--- a/programs/ssl/dtls_client.c
+++ b/programs/ssl/dtls_client.c
@@ -59,6 +59,7 @@
 #include "mbedtls/ctr_drbg.h"
 #include "mbedtls/error.h"
 #include "mbedtls/certs.h"
+#include "mbedtls/timing.h"
 
 #define SERVER_PORT 4433
 #define SERVER_NAME "localhost"