diff --git a/include/mbedtls/x509.h b/include/mbedtls/x509.h
index 7faf176..8582e76 100644
--- a/include/mbedtls/x509.h
+++ b/include/mbedtls/x509.h
@@ -312,6 +312,12 @@
 }
 mbedtls_x509_subject_alternative_name;
 
+typedef struct mbedtls_x509_san_list {
+    mbedtls_x509_subject_alternative_name node;
+    struct mbedtls_x509_san_list *next;
+}
+mbedtls_x509_san_list;
+
 /** \} name Structures for parsing X.509 certificates, CRLs and CSRs */
 
 /**
@@ -467,6 +473,7 @@
                                size_t val_len);
 int mbedtls_x509_write_extensions(unsigned char **p, unsigned char *start,
                                   mbedtls_asn1_named_data *first);
+
 int mbedtls_x509_write_names(unsigned char **p, unsigned char *start,
                              mbedtls_asn1_named_data *first);
 int mbedtls_x509_write_sig(unsigned char **p, unsigned char *start,