diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index ddab63e..d5bb6a7 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -62,32 +62,41 @@
     mbedtls_mpi_uint mpi_uint;
 
     TEST_INVALID_PARAM( mbedtls_mpi_init( NULL ) );
+    TEST_VALID_PARAM( mbedtls_mpi_free( NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_grow( NULL, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_copy( NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_copy( &X, NULL ) );
+
     TEST_INVALID_PARAM( mbedtls_mpi_swap( NULL, &X ) );
     TEST_INVALID_PARAM( mbedtls_mpi_swap( &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_safe_cond_assign( NULL, &X, 0 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_safe_cond_assign( &X, NULL, 0 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_safe_cond_swap( NULL, &X, 0 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_safe_cond_swap( &X, NULL, 0 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_lset( NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_get_bit( NULL, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_set_bit( NULL, 42, 0 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_read_string( NULL, 2, s_in ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_read_string( &X, 2, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_write_string( NULL, 2,
                                                       s_out, sizeof( s_out ),
@@ -100,11 +109,13 @@
                             mbedtls_mpi_write_string( &X, 2,
                                                       s_out, sizeof( s_out ),
                                                       NULL ) );
+
 #if defined(MBEDTLS_FS_IO)
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_read_file( NULL, 2, stdin ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_read_file( &X, 2, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_write_file( "", NULL, 2, NULL ) );
 #endif /* MBEDTLS_FS_IO */
@@ -115,84 +126,102 @@
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_read_binary( &X, NULL,
                                                      sizeof( u_in ) ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_write_binary( NULL, u_out,
                                                       sizeof( u_out ) ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_write_binary( &X, NULL,
                                                       sizeof( u_out ) ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_shift_l( NULL, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_shift_r( NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_cmp_abs( NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_cmp_abs( &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_cmp_mpi( NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_cmp_mpi( &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_cmp_int( NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_abs( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_abs( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_abs( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_abs( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_abs( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_abs( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_mpi( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_mpi( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_mpi( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_mpi( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_mpi( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_mpi( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_int( NULL, &X, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_add_int( &X, NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_int( NULL, &X, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_sub_int( &X, NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mul_mpi( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mul_mpi( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mul_mpi( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mul_int( NULL, &X, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mul_int( &X, NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_div_mpi( &X, &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_div_mpi( &X, &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_div_int( &X, &X, NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mod_mpi( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mod_mpi( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mod_mpi( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mod_int( NULL, &X, 42 ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_mod_int( &mpi_uint, NULL, 42 ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_exp_mod( NULL, &X, &X, &X, NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
@@ -201,23 +230,26 @@
                             mbedtls_mpi_exp_mod( &X, &X, NULL, &X, NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_exp_mod( &X, &X, &X, NULL, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_fill_random( NULL, 42, rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_fill_random( &X, 42, NULL, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_gcd( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_gcd( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_gcd( &X, &X, NULL ) );
+
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_inv_mod( NULL, &X, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                             mbedtls_mpi_inv_mod( &X, NULL, &X ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
-                            mbedtls_mpi_inv_mod( NULL, &X, &X ) );
+                            mbedtls_mpi_inv_mod( &X, &X, NULL ) );
 
     mbedtls_mpi_free( NULL );