Improved on the fix of #309 and extended the test to cover subroutines.
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index e972020..c0fdf8e 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -443,15 +443,24 @@
 void mpi_add_mpi_inplace( int radix_X, char *input_X, int radix_A, char *input_A )
 {
     mpi X, A;
-    mpi_init( &X ); mbedtls_mpi_init( &A );
+    mpi_init( &X ); mpi_init( &A );
+
+    TEST_ASSERT( mpi_read_string( &A, radix_A, input_A ) == 0 );
 
     TEST_ASSERT( mpi_read_string( &X, radix_X, input_X ) == 0 );
-    TEST_ASSERT( mpi_read_string( &A, radix_A, input_A ) == 0 );
+    TEST_ASSERT( mpi_sub_abs( &X, &X, &X ) == 0 );
+    TEST_ASSERT( mpi_cmp_int( &X, 0 ) == 0 );
+
+    TEST_ASSERT( mpi_read_string( &X, radix_X, input_X ) == 0 );
+    TEST_ASSERT( mpi_add_abs( &X, &X, &X ) == 0 );
+    TEST_ASSERT( mpi_cmp_mpi( &X, &A ) == 0 );
+
+    TEST_ASSERT( mpi_read_string( &X, radix_X, input_X ) == 0 );
     TEST_ASSERT( mpi_add_mpi( &X, &X, &X ) == 0 );
     TEST_ASSERT( mpi_cmp_mpi( &X, &A ) == 0 );
 
 exit:
-    mpi_free( &X ); mbedtls_mpi_free( &A );
+    mpi_free( &X ); mpi_free( &A );
 }
 /* END_CASE */