diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index caf1199..ec0814a 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -40,14 +40,10 @@
 
 #include "mbedtls/ssl_cookie.h"
 #include "mbedtls/ssl_internal.h"
+#include "mbedtls/utils.h"
 
 #include <string.h>
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
 /*
  * If DTLS is in use, then at least one of SHA-1, SHA-256, SHA-512 is
  * available. Try SHA-256 first, 512 wastes resources since we need to stay