diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index 786a3bb..db51887 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -982,10 +982,21 @@
 
 /** The Electronic Code Book (ECB) mode of a block cipher, with no padding.
  *
+ * \warning ECB mode does not protect the confidentiality of the encrypted data
+ * except in extremely narrow circumstances. It is recommended that applications
+ * only use ECB if they need to construct an operating mode that the
+ * implementation does not provide. Implementations are encouraged to provide
+ * the modes that applications need in preference to supporting direct access
+ * to ECB.
+ *
  * The underlying block cipher is determined by the key type.
  *
- * This symmetric cipher mode can only be used with messages whose lengths
- * are whole number of blocks for the chosen block cipher.
+ * This symmetric cipher mode can only be used with messages whose lengths are a
+ * multiple of the block size of the chosen block cipher.
+ *
+ * ECB mode does not accept an initialization vector (IV). When using a
+ * multi-part cipher operation with this algorithm, psa_cipher_generate_iv()
+ * and psa_cipher_set_iv() must not be called.
  */
 #define PSA_ALG_ECB_NO_PADDING                  ((psa_algorithm_t)0x04404400)