diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index a316166..c8eb08b 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -146,11 +146,11 @@
  * linkage). This function may be provided as a function-like macro,
  * but in this case it must evaluate each of its arguments exactly once.
  *
- * \param[out] attributes       The attribute structure to write to.
- * \param id                    The persistent identifier for the key.
+ * \param[out] attributes  The attribute structure to write to.
+ * \param key              The persistent identifier for the key.
  */
 static void psa_set_key_id(psa_key_attributes_t *attributes,
-                           psa_key_id_t id);
+                           psa_key_file_id_t key);
 
 /** Set the location of a persistent key.
  *
@@ -192,7 +192,7 @@
  *         This value is unspecified if the attribute structure declares
  *         the key as volatile.
  */
-static psa_key_id_t psa_get_key_id(const psa_key_attributes_t *attributes);
+static psa_key_file_id_t psa_get_key_id(const psa_key_attributes_t *attributes);
 
 /** Retrieve the lifetime from key attributes.
  *
@@ -392,8 +392,9 @@
  * with a lifetime other than #PSA_KEY_LIFETIME_VOLATILE. A persistent key
  * always has a nonzero key identifier, set with psa_set_key_id() when
  * creating the key. Implementations may provide additional pre-provisioned
- * keys that can be opened with psa_open_key(). Such keys have a key identifier
- * in the vendor range, as documented in the description of #psa_key_id_t.
+ * keys that can be opened with psa_open_key(). Such keys have an application
+ * key identifier in the vendor range, as documented in the description of
+ * #psa_key_id_t.
  *
  * The application must eventually close the handle with psa_close_key() or
  * psa_destroy_key() to release associated resources. If the application dies
@@ -408,7 +409,7 @@
  * portable to implementations that only permit a single key handle to be
  * opened. See also :ref:\`key-handles\`.
  *
- * \param id            The persistent identifier of the key.
+ * \param key           The persistent identifier of the key.
  * \param[out] handle   On success, a handle to the key.
  *
  * \retval #PSA_SUCCESS
@@ -436,8 +437,7 @@
  *         It is implementation-dependent whether a failure to initialize
  *         results in this error code.
  */
-psa_status_t psa_open_key(psa_key_id_t id,
-                          psa_key_handle_t *handle);
+psa_status_t psa_open_key(psa_key_file_id_t key, psa_key_handle_t *handle);
 
 
 /** Close a key handle.
diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index 67c53db..267b050 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -330,7 +330,7 @@
     psa_key_type_t type;
     psa_key_bits_t bits;
     psa_key_lifetime_t lifetime;
-    psa_key_id_t id;
+    psa_key_file_id_t id;
     psa_key_policy_t policy;
     psa_key_attributes_flag_t flags;
 } psa_core_key_attributes_t;
@@ -360,14 +360,14 @@
 }
 
 static inline void psa_set_key_id(psa_key_attributes_t *attributes,
-                                  psa_key_id_t id)
+                                  psa_key_file_id_t key)
 {
-    attributes->core.id = id;
+    attributes->core.id = key;
     if( attributes->core.lifetime == PSA_KEY_LIFETIME_VOLATILE )
         attributes->core.lifetime = PSA_KEY_LIFETIME_PERSISTENT;
 }
 
-static inline psa_key_id_t psa_get_key_id(
+static inline psa_key_file_id_t psa_get_key_id(
     const psa_key_attributes_t *attributes)
 {
     return( attributes->core.id );
diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index f8811ad..4603a1d 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -37,6 +37,11 @@
 
 #include <stdint.h>
 
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
+#define inline __inline
+#endif
+
 /** \defgroup error Error codes
  * @{
  */
@@ -125,7 +130,7 @@
  * implementation-specific device management event occurs (for example,
  * a factory reset).
  *
- * Persistent keys have a key identifier of type #psa_key_id_t.
+ * Persistent keys have a key identifier of type #psa_key_file_id_t.
  * This identifier remains valid throughout the lifetime of the key,
  * even if the application instance that created the key terminates.
  * The application can call psa_open_key() to open a persistent key that
@@ -239,6 +244,19 @@
 #define PSA_KEY_ID_INIT 0
 #define PSA_KEY_FILE_GET_KEY_ID( id ) ( id )
 
+/** Utility to initialize a key file identifier at runtime.
+ *
+ * \param unused  Unused parameter.
+ * \param key_id  Identifier of the key.
+ */
+static inline psa_key_file_id_t psa_key_file_id_make(
+    unsigned int unused, psa_key_id_t key_id )
+{
+    (void)unused;
+
+    return( key_id );
+}
+
 #else /* MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER */
 typedef struct
 {
@@ -246,16 +264,21 @@
     psa_key_owner_id_t owner;
 } psa_key_file_id_t;
 
-/* Since crypto.h is used as part of the PSA Cryptography API specification,
- * it must use standard types for things like the argument of psa_open_key().
- * If it wasn't for that constraint, psa_open_key() would take a
- * `psa_key_file_id_t` argument. As a workaround, make `psa_key_id_t` an
- * alias for `psa_key_file_id_t` when building for a multi-client service. */
-typedef psa_key_file_id_t psa_key_id_t;
-
 #define PSA_KEY_ID_INIT {0, 0}
 #define PSA_KEY_FILE_GET_KEY_ID( file_id ) ( ( file_id ).key_id )
 
+/** Utility to initialize a key file identifier at runtime.
+ *
+ * \param owner_id Identifier of the key owner.
+ * \param key_id   Identifier of the key.
+ */
+static inline psa_key_file_id_t psa_key_file_id_make(
+    psa_key_owner_id_t owner_id, uint32_t key_id )
+{
+    return( (psa_key_file_id_t){ .key_id = key_id,
+                                 .owner = owner_id } );
+}
+
 #endif /* !MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER */
 
 /**@}*/