diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 6a7d502..1076dea 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -518,7 +518,7 @@
         switch (ret) {
             case 0: /*ok*/
                 break;
-            case MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG + MBEDTLS_ERR_OID_NOT_FOUND:
+            case MBEDTLS_ERR_OID_NOT_FOUND:
                 /* Ignore certificate with an unknown algorithm: maybe a
                    prior certificate was already trusted. */
                 break;