diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index dee77b8..b1ef216 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -37,7 +37,7 @@
 #include "mbedtls/oid.h"
 #include "mbedtls/asn1write.h"
 #include "mbedtls/sha1.h"
-#include "mbedtls/utils.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -61,7 +61,7 @@
     mbedtls_asn1_free_named_data_list( &ctx->issuer );
     mbedtls_asn1_free_named_data_list( &ctx->extensions );
 
-    mbedtls_zeroize( ctx, sizeof( mbedtls_x509write_cert ) );
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_cert ) );
 }
 
 void mbedtls_x509write_crt_set_version( mbedtls_x509write_cert *ctx, int version )