diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index f0e4782..4329bf8 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -428,8 +428,9 @@
  * #PSA_KEY_TYPE_DH_KEY_PAIR(#PSA_DH_GROUP_CUSTOM), the group data comes
  * from domain parameters set by psa_set_key_domain_parameters().
  */
-/* This value is reserved for private use in the TLS named group registry. */
-#define PSA_DH_GROUP_CUSTOM             ((psa_dh_group_t) 0x01fc)
+/* This value is a deprecated value meaning an explicit curve in the IANA
+ * registry. */
+#define PSA_DH_GROUP_CUSTOM             ((psa_dh_group_t) 0xff01)
 
 
 /**