diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index 4bacdad..6cc281a 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -413,8 +413,8 @@
         return MBEDTLS_ERR_X509_INVALID_ALG;
     }
 
-    if ((ret = mbedtls_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
-                                              &sig_oid, &sig_oid_len)) != 0) {
+    if ((ret = mbedtls_x509_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
+                                                   &sig_oid, &sig_oid_len)) != 0) {
         return ret;
     }