diff --git a/crypto/ecdsa/ecs_vrf.c b/crypto/ecdsa/ecs_vrf.c
index 2836efe5e..188b9d57b 100644
--- a/crypto/ecdsa/ecs_vrf.c
+++ b/crypto/ecdsa/ecs_vrf.c
@@ -57,7 +57,7 @@
  */
 
 #include "ecs_locl.h"
-#include "cryptlib.h"
+#include <string.h>
 #ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
 #endif