diff --git a/programs/ssl/dtls_server.c b/programs/ssl/dtls_server.c
index 12b2731..4eabf98 100644
--- a/programs/ssl/dtls_server.c
+++ b/programs/ssl/dtls_server.c
@@ -70,6 +70,7 @@
 #include "mbedtls/net.h"
 #include "mbedtls/error.h"
 #include "mbedtls/debug.h"
+#include "mbedtls/timing.h"
 
 #if defined(MBEDTLS_SSL_CACHE_C)
 #include "mbedtls/ssl_cache.h"