diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index 44c7c66..ced42de 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -107,8 +107,8 @@
  *   #PSA_KEY_ID_USER_MIN to #PSA_KEY_ID_USER_MAX.
  * - Implementations may define additional key identifiers in the range
  *   #PSA_KEY_ID_VENDOR_MIN to #PSA_KEY_ID_VENDOR_MAX.
- * - Key identifiers outside these ranges are reserved for future use
- *   in future versions of this specification.
+ * - 0 is reserved as an invalid key identifier.
+ * - Key identifiers outside these ranges are reserved for future use.
  */
 /* Implementation-specific quirk: The Mbed Crypto library can be built as
  * part of a multi-client service that exposes the PSA Crypto API in each
diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index 40172b3..2ee8839 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -1442,7 +1442,7 @@
 
 /** The minimum value for a key identifier chosen by the application.
  */
-#define PSA_KEY_ID_USER_MIN                     ((psa_key_id_t)0x00000000)
+#define PSA_KEY_ID_USER_MIN                     ((psa_key_id_t)0x00000001)
 /** The minimum value for a key identifier chosen by the application.
  */
 #define PSA_KEY_ID_USER_MAX                     ((psa_key_id_t)0x3fffffff)