diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index 41dfe87..dee77b8 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -37,6 +37,7 @@
 #include "mbedtls/oid.h"
 #include "mbedtls/asn1write.h"
 #include "mbedtls/sha1.h"
+#include "mbedtls/utils.h"
 
 #include <string.h>
 
@@ -44,11 +45,6 @@
 #include "mbedtls/pem.h"
 #endif /* MBEDTLS_PEM_WRITE_C */
 
-/* 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;
-}
-
 void mbedtls_x509write_crt_init( mbedtls_x509write_cert *ctx )
 {
     memset( ctx, 0, sizeof( mbedtls_x509write_cert ) );