diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index c3531e404a..1f5ab0d557 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -5575,11 +5575,14 @@ static psa_status_t psa_key_derivation_pbkdf2_generate_block(
     memcpy(U_accumulator, U_i, prf_output_length);
 
     for (i = 1; i < pbkdf2->input_cost; i++) {
+        /* We are passing prf_output_length as mac_size because the driver
+         * function directly sets mac_output_length as mac_size upon success.
+         * See #7801 */
         status = psa_driver_wrapper_mac_compute(attributes,
                                                 pbkdf2->password,
                                                 pbkdf2->password_length,
                                                 prf_alg, U_i, prf_output_length,
-                                                U_i, sizeof(U_i),
+                                                U_i, prf_output_length,
                                                 &mac_output_length);
         if (status != PSA_SUCCESS) {
             goto cleanup;