diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index af1ab37..d916cff 100755
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -711,7 +711,7 @@
  * - A failed call to psa_hash_update().
  * - A call to psa_hash_finish(), psa_hash_verify() or psa_hash_abort().
  *
- * \param operation
+ * \param operation The operation object to use.
  * \param alg       The hash algorithm to compute (\c PSA_ALG_XXX value
  *                  such that #PSA_ALG_IS_HASH(alg) is true).
  *
@@ -904,7 +904,7 @@
  * - A failed call to psa_mac_update().
  * - A call to psa_mac_finish(), psa_mac_verify() or psa_mac_abort().
  *
- * \param operation
+ * \param operation The operation object to use.
  * \param alg       The MAC algorithm to compute (\c PSA_ALG_XXX value
  *                  such that #PSA_ALG_IS_MAC(alg) is true).
  *
@@ -980,7 +980,7 @@
  *   or psa_cipher_update().
  * - A call to psa_cipher_finish() or psa_cipher_abort().
  *
- * \param operation
+ * \param operation The operation object to use.
  * \param alg       The cipher algorithm to compute (\c PSA_ALG_XXX value
  *                  such that #PSA_ALG_IS_CIPHER(alg) is true).
  *
@@ -1027,7 +1027,7 @@
  * - A failed call to psa_cipher_update().
  * - A call to psa_cipher_finish() or psa_cipher_abort().
  *
- * \param operation
+ * \param operation The operation object to use.
  * \param alg       The cipher algorithm to compute (\c PSA_ALG_XXX value
  *                  such that #PSA_ALG_IS_CIPHER(alg) is true).
  *