diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index e65ddb0..6540305 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -63,6 +63,7 @@
 int mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr *ctx,
                                            const char *subject_name)
 {
+    mbedtls_asn1_free_named_data_list(&ctx->subject);
     return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
 }