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)
diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index 2ef70db..22cac61 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -185,15 +185,14 @@
                                 int vendor_ok )
 {
     psa_app_key_id_t key_id = PSA_KEY_FILE_GET_KEY_ID( file_id );
-    /* Reject high values because the file names are reserved for the
-     * library's internal use. */
-    if( key_id > PSA_MAX_PERSISTENT_KEY_IDENTIFIER )
+    if( PSA_KEY_ID_USER_MIN <= key_id && key_id <= PSA_KEY_ID_USER_MAX )
+        return( 1 );
+    else if( vendor_ok &&
+             PSA_KEY_ID_VENDOR_MIN <= key_id &&
+             key_id <= PSA_KEY_ID_VENDOR_MAX )
+        return( 1 );
+    else
         return( 0 );
-    /* Applications may only create keys in the range
-     * 0..PSA_KEY_ID_USER_MAX. */
-    if( ! vendor_ok && key_id > PSA_KEY_ID_USER_MAX )
-        return( 0 );
-    return( 1 );
 }
 
 /** Declare a slot as persistent and load it from storage.
diff --git a/tests/suites/test_suite_psa_crypto_slot_management.data b/tests/suites/test_suite_psa_crypto_slot_management.data
index 519e81e..ecfb37a 100644
--- a/tests/suites/test_suite_psa_crypto_slot_management.data
+++ b/tests/suites/test_suite_psa_crypto_slot_management.data
@@ -34,6 +34,10 @@
 Attempt to overwrite: keep open
 create_existent:PSA_KEY_LIFETIME_PERSISTENT:1:KEEP_OPEN
 
+Open failure: invalid identifier (0)
+depends_on:MBEDTLS_PSA_CRYPTO_STORAGE_C
+open_fail:0:PSA_ERROR_INVALID_ARGUMENT
+
 Open failure: invalid identifier (random seed UID)
 depends_on:MBEDTLS_PSA_CRYPTO_STORAGE_C
 open_fail:PSA_CRYPTO_ITS_RANDOM_SEED_UID:PSA_ERROR_INVALID_ARGUMENT
@@ -53,6 +57,10 @@
 Create failure: invalid lifetime
 create_fail:0x7fffffff:0:PSA_ERROR_INVALID_ARGUMENT
 
+Create failure: invalid key id (0)
+depends_on:MBEDTLS_PSA_CRYPTO_STORAGE_C
+create_fail:PSA_KEY_LIFETIME_PERSISTENT:0:PSA_ERROR_INVALID_ARGUMENT
+
 Create failure: invalid key id (random seed UID)
 depends_on:MBEDTLS_PSA_CRYPTO_STORAGE_C
 create_fail:PSA_KEY_LIFETIME_PERSISTENT:PSA_CRYPTO_ITS_RANDOM_SEED_UID:PSA_ERROR_INVALID_ARGUMENT