diff --git a/tests/suites/test_suite_bignum_mod_raw.function b/tests/suites/test_suite_bignum_mod_raw.function
index 4adccce..cf385e0 100644
--- a/tests/suites/test_suite_bignum_mod_raw.function
+++ b/tests/suites/test_suite_bignum_mod_raw.function
@@ -287,6 +287,97 @@
 
 /* BEGIN MERGE SLOT 5 */
 
+/* BEGIN_CASE */
+void mpi_mod_raw_add( char * input_A, char * input_B,
+                      char * input_N, char * input_S )
+{
+    mbedtls_mpi_uint *A = NULL;
+    mbedtls_mpi_uint *B = NULL;
+    mbedtls_mpi_uint *S = NULL;
+    mbedtls_mpi_uint *N = NULL;
+    mbedtls_mpi_uint *X = NULL;
+    mbedtls_mpi_mod_modulus m;
+    size_t A_limbs, B_limbs, N_limbs, S_limbs;
+
+    mbedtls_mpi_mod_modulus_init( &m );
+
+    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &A, &A_limbs, input_A ) );
+    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &B, &B_limbs, input_B ) );
+    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &N, &N_limbs, input_N ) );
+    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &S, &S_limbs, input_S ) );
+
+    /* All inputs must have have the same number of limbs. */
+    TEST_EQUAL( A_limbs, B_limbs );
+    TEST_EQUAL( S_limbs, N_limbs );
+    TEST_EQUAL( A_limbs, S_limbs );
+
+    size_t limbs = A_limbs;
+    size_t bytes = limbs * sizeof( *A );
+
+    ASSERT_ALLOC( X, limbs );
+
+    TEST_EQUAL( mbedtls_mpi_mod_modulus_setup(
+                        &m, N, limbs,
+                        MBEDTLS_MPI_MOD_EXT_REP_BE,
+                        MBEDTLS_MPI_MOD_REP_MONTGOMERY
+                ), 0 );
+
+    /* A + B => Correct result */
+    mbedtls_mpi_mod_raw_add( X, A, B, &m );
+    ASSERT_COMPARE( X, bytes, S, bytes );
+
+    /* A + B: alias X to A => Correct result */
+    memcpy( X, A, bytes );
+    mbedtls_mpi_mod_raw_add( X, X, B, &m );
+    ASSERT_COMPARE( X, bytes, S, bytes );
+
+    /* A + B: alias X to B => Correct result */
+    memcpy( X, B, bytes );
+    mbedtls_mpi_mod_raw_add( X, A, X, &m );
+    ASSERT_COMPARE( X, bytes, S, bytes );
+
+    if ( memcmp(A, B, bytes ) == 0 )
+    {
+        /* A == B: alias A and B */
+
+        /* A + A => Correct result */
+        mbedtls_mpi_mod_raw_add( X, A, A, &m );
+        ASSERT_COMPARE( X, bytes, S, bytes );
+
+        /* A + A, alias X to A => Correct result */
+        memcpy( X, A, bytes );
+        mbedtls_mpi_mod_raw_add( X, A, A, &m );
+        ASSERT_COMPARE( X, bytes, S, bytes );
+    }
+    else
+    {
+        /* A != B: test B + A */
+
+        /* B + A => Correct result */
+        mbedtls_mpi_mod_raw_add( X, B, A, &m );
+        ASSERT_COMPARE( X, bytes, S, bytes );
+
+        /* B + A: alias X to A => Correct result */
+        memcpy( X, A, bytes );
+        mbedtls_mpi_mod_raw_add( X, B, X, &m );
+        ASSERT_COMPARE( X, bytes, S, bytes );
+
+        /* B + A: alias X to B => Correct result */
+        memcpy( X, B, bytes );
+        mbedtls_mpi_mod_raw_add( X, X, A, &m );
+        ASSERT_COMPARE( X, bytes, S, bytes );
+    }
+
+exit:
+    mbedtls_free( A );
+    mbedtls_free( B );
+    mbedtls_free( S );
+    mbedtls_free( N );
+    mbedtls_free( X );
+
+    mbedtls_mpi_mod_modulus_free( &m );
+}
+/* END_CASE */
 /* END MERGE SLOT 5 */
 
 /* BEGIN MERGE SLOT 6 */