diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index 6dfaa13..5359b58 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -104,6 +104,67 @@
     return( attributes->core.policy.alg2 );
 }
 
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+
+/** Retrieve the slot number where a key is stored.
+ *
+ * A slot number is only defined for keys that are stored in a secure
+ * element.
+ *
+ * This information is only useful if the secure element is not entirely
+ * managed through the PSA Cryptography API. It is up to the secure
+ * element driver to decide how PSA slot numbers map to any other interface
+ * that the secure element may have.
+ *
+ * \param[in] attributes        The key attribute structure to query.
+ * \param[out] slot_number      On success, the slot number containing the key.
+ *
+ * \retval #PSA_SUCCESS
+ *         The key is located in a secure element, and \p *slot_number
+ *         indicates the slot number that contains it.
+ * \retval #PSA_ERROR_NOT_PERMITTED
+ *         The caller is not permitted to query the slot number.
+ *         Mbed Crypto currently does not return this error.
+ * \retval #PSA_ERROR_INVALID_ARGUMENT
+ *         The key is not located in a secure element.
+ */
+psa_status_t psa_get_key_slot_number(
+    const psa_key_attributes_t *attributes,
+    psa_key_slot_number_t *slot_number );
+
+/** Choose the slot number where a key is stored.
+ *
+ * This function declares a slot number in the specified attribute
+ * structure.
+ *
+ * A slot number is only meaningful for keys that are stored in a secure
+ * element. It is up to the secure element driver to decide how PSA slot
+ * numbers map to any other interface that the secure element may have.
+ *
+ * \note Setting a slot number in key attributes for a key creation can
+ *       cause the following errors when creating the key:
+ *       - #PSA_ERROR_NOT_SUPPORTED if the selected secure element does
+ *         not support choosing a specific slot number.
+ *       - #PSA_ERROR_NOT_PERMITTED if the caller is not permitted to
+ *         choose slot numbers in general or to choose this specific slot.
+ *       - #PSA_ERROR_INVALID_ARGUMENT if the chosen slot number is not
+ *         valid in general or not valid for this specific key.
+ *       - #PSA_ERROR_ALREADY_EXISTS if there is already a key in the
+ *         selected slot.
+ *
+ * \param[out] attributes       The attribute structure to write to.
+ * \param slot_number           The slot number to set.
+ */
+static inline void psa_set_key_slot_number(
+    psa_key_attributes_t *attributes,
+    psa_key_slot_number_t slot_number )
+{
+    attributes->core.flags |= MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER;
+    attributes->slot_number = slot_number;
+}
+
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+
 /**@}*/
 
 /**
diff --git a/include/psa/crypto_se_driver.h b/include/psa/crypto_se_driver.h
index f95eaeb..69cdaba 100644
--- a/include/psa/crypto_se_driver.h
+++ b/include/psa/crypto_se_driver.h
@@ -134,10 +134,17 @@
                                           void *persistent_data,
                                           psa_key_lifetime_t lifetime);
 
+#if defined(__DOXYGEN_ONLY__) || !defined(MBEDTLS_PSA_CRYPTO_SE_C)
+/* Mbed Crypto with secure element support enabled defines this type in
+ * crypto_types.h because it is also visible to applications through an
+ * implementation-specific extension.
+ * For the PSA Cryptography specification, this type is only visible
+ * via crypto_se_driver.h. */
 /** An internal designation of a key slot between the core part of the
  * PSA Crypto implementation and the driver. The meaning of this value
  * is driver-dependent. */
 typedef uint64_t psa_key_slot_number_t;
+#endif /* __DOXYGEN_ONLY__ || !MBEDTLS_PSA_CRYPTO_SE_C */
 
 /**@}*/
 
diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index 3bace60..fbfe77e 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -331,11 +331,13 @@
  */
 typedef uint16_t psa_key_attributes_flag_t;
 
-#define MBEDLTS_PSA_KA_FLAG_SLOT_NUMBER ( (psa_key_attributes_flag_t) 0x0001 )
+#define MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER     \
+    ( (psa_key_attributes_flag_t) 0x0001 )
 
 /* A mask of key attribute flags used externally only.
  * Only meant for internal checks inside the library. */
 #define MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY (      \
+        MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER |    \
         0 )
 
 /* A mask of key attribute flags used both internally and externally.
@@ -358,11 +360,19 @@
 struct psa_key_attributes_s
 {
     psa_core_key_attributes_t core;
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+    psa_key_slot_number_t slot_number;
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
     void *domain_parameters;
     size_t domain_parameters_size;
 };
 
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, 0, NULL, 0}
+#else
 #define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, NULL, 0}
+#endif
+
 static inline struct psa_key_attributes_s psa_key_attributes_init( void )
 {
     const struct psa_key_attributes_s v = PSA_KEY_ATTRIBUTES_INIT;
diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index 1944be4..9af4957 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -244,6 +244,17 @@
  */
 typedef struct psa_key_attributes_s psa_key_attributes_t;
 
+
+#ifndef __DOXYGEN_ONLY__
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+/* Mbed Crypto defines this type in crypto_types.h because it is also
+ * visible to applications through an implementation-specific extension.
+ * For the PSA Cryptography specification, this type is only visible
+ * via crypto_se_driver.h. */
+typedef uint64_t psa_key_slot_number_t;
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+#endif /* !__DOXYGEN_ONLY__ */
+
 /**@}*/
 
 /** \defgroup derivation Key derivation