diff --git a/include/mbedtls/oid.h b/include/mbedtls/oid.h
index 3a7f740..de8e454 100644
--- a/include/mbedtls/oid.h
+++ b/include/mbedtls/oid.h
@@ -300,7 +300,9 @@
 #define MBEDTLS_OID_HMAC_RIPEMD160              MBEDTLS_OID_INTERNET "\x05\x05\x08\x01\x04" /**< id-hmacWithSHA1 OBJECT IDENTIFIER ::= {iso(1) iso-identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) ipsec(8) isakmpOakley(1) hmacRIPEMD160(4)} */
 
 /*
- * Encryption algorithms
+ * Encryption algorithms,
+ * the following standardized object identifiers are specified at
+ * https://datatracker.ietf.org/doc/html/rfc8018#appendix-C.
  */
 #define MBEDTLS_OID_DES_CBC                     MBEDTLS_OID_ISO_IDENTIFIED_ORG \
         MBEDTLS_OID_OIW_SECSIG_ALG "\x07"                                                                        /**< desCBC OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) oiw(14) secsig(3) algorithms(2) 7 } */