diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index f8b8cea..089484f 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -1057,12 +1057,15 @@
 
 psa_status_t psa_cipher_update(psa_cipher_operation_t *operation,
                                const uint8_t *input,
-                               size_t input_length);
+                               size_t input_length,
+                               unsigned char *output, 
+                               size_t output_size, 
+                               size_t *output_length);
 
 psa_status_t psa_cipher_finish(psa_cipher_operation_t *operation,
-                               uint8_t *mac,
-                               size_t mac_size,
-                               size_t *mac_length);
+                               uint8_t *output,
+                               size_t output_size,
+                               size_t *output_length);
 
 psa_status_t psa_cipher_abort(psa_cipher_operation_t *operation);
 
diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index eba4862..2975bdc 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -106,7 +106,7 @@
     uint8_t block_size;
     union
     {
-        unsigned dummy; /* Make the union non-empty even with no supported algorithms. */
+        mbedtls_cipher_context_t cipher;
     } ctx;
 };