diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index fa1d3cf..097361a 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1156,6 +1156,21 @@
  */
 //#define MBEDTLS_PSA_HAS_ITS_IO
 
+/* MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER
+ *
+ * In PSA key storage, encode the owner of the key.
+ *
+ * This is only meaningful when building the library as part of a
+ * multi-client service. When you activate this option, you must provide
+ * an implementation of the type psa_key_owner_id_t and a translation
+ * from psa_key_file_id_t to file name in all the storage backends that
+ * you wish to support.
+ *
+ * Note that this option is meant for internal use only and may be removed
+ * without notice.
+ */
+//#define MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER
+
 /**
  * \def MBEDTLS_MEMORY_DEBUG
  *