diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index 8395f74..bf25c4c 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -583,10 +583,10 @@
                 } else if (strcmp(q, "DNS") == 0) {
                     cur->node.type = MBEDTLS_X509_SAN_DNS_NAME;
                 } else if (strcmp(q, "IP") == 0) {
-                    size_t ip_len = 0;
+                    size_t ip_addr_len = 0;
                     cur->node.type = MBEDTLS_X509_SAN_IP_ADDRESS;
-                    ip_len = mbedtls_x509_crt_parse_cn_inet_pton(subtype_value, ip);
-                    if (ip_len == 0) {
+                    ip_addr_len = mbedtls_x509_crt_parse_cn_inet_pton(subtype_value, ip);
+                    if (ip_addr_len == 0) {
                         mbedtls_printf("mbedtls_x509_crt_parse_cn_inet_pton failed to parse %s\n",
                                        subtype_value);
                         goto exit;