diff --git a/library/psa_crypto_core.h b/library/psa_crypto_core.h
index 1edd63e..7b16724 100644
--- a/library/psa_crypto_core.h
+++ b/library/psa_crypto_core.h
@@ -117,6 +117,8 @@
         0)
 
 /** Test whether a key slot has any registered readers.
+ * If multi-threading is enabled, the caller must hold the
+ * global key slot mutex.
  *
  * \param[in] slot      The key slot to test.
  *
@@ -195,6 +197,8 @@
  *
  * Persistent storage is not affected.
  * Sets the slot's state to PSA_SLOT_EMPTY.
+ * If multi-threading is enabled, the caller must hold the
+ * global key slot mutex.
  *
  * \param[in,out] slot  The key slot to wipe.
  *
diff --git a/library/psa_crypto_slot_management.h b/library/psa_crypto_slot_management.h
index 01778f8..fc46257 100644
--- a/library/psa_crypto_slot_management.h
+++ b/library/psa_crypto_slot_management.h
@@ -134,6 +134,9 @@
  * new state. If the state of the slot was not expected_state, the state is
  * unchanged.
  *
+ * If multi-threading is enabled, the caller must hold the
+ * global key slot mutex.
+ *
  * \param[in] slot            The key slot.
  * \param[in] expected_state  The current state of the slot.
  * \param[in] new_state       The new state of the slot.
@@ -157,7 +160,8 @@
 /** Register as a reader of a key slot.
  *
  * This function increments the key slot registered reader counter by one.
- *
+ * If multi-threading is enabled, the caller must hold the
+ * global key slot mutex.
  * \param[in] slot  The key slot.
  *
  * \retval #PSA_SUCCESS
@@ -182,7 +186,9 @@
  * This function decrements the key slot registered reader counter by one.
  * If the state of the slot is PSA_SLOT_PENDING_DELETION,
  * and there is only one registered reader (the caller),
- * this function will call psa_wipe_key_slot().
+ * this function will call psa_wipe_slot().
+ * If multi-threading is enabled, the caller must hold the
+ * global key slot mutex.
  *
  * \note To ease the handling of errors in retrieving a key slot
  *       a NULL input pointer is valid, and the function returns