diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index fe10ee0..fd1928a 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -415,7 +415,9 @@
  * \retval #PSA_ERROR_BAD_STATE
  *         The library has not been previously initialized by psa_crypto_init().
  *         It is implementation-dependent whether a failure to initialize
- *         results in this error code.
+ *         results in this error code. Or,
+ *         this call was operating on a key slot and found the slot in
+ *         an invalid state for the operation.
  */
 psa_status_t psa_purge_key(mbedtls_svc_key_id_t key);
 
@@ -555,7 +557,9 @@
  * \retval #PSA_ERROR_BAD_STATE
  *         The library has not been previously initialized by psa_crypto_init().
  *         It is implementation-dependent whether a failure to initialize
- *         results in this error code.
+ *         results in this error code. Or,
+ *         this call was operating on a key slot and found the slot in
+ *         an invalid state for the operation.
  */
 psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key);
 
diff --git a/include/psa/crypto_compat.h b/include/psa/crypto_compat.h
index f896fae..bfc0016 100644
--- a/include/psa/crypto_compat.h
+++ b/include/psa/crypto_compat.h
@@ -142,7 +142,9 @@
  * \retval #PSA_ERROR_BAD_STATE
  *         The library has not been previously initialized by psa_crypto_init().
  *         It is implementation-dependent whether a failure to initialize
- *         results in this error code.
+ *         results in this error code. Or,
+ *         this call was operating on a key slot and found the slot in
+ *         an invalid state for the operation.
  */
 psa_status_t psa_close_key(psa_key_handle_t handle);