diff --git a/tests/suites/test_suite_bignum_mod.function b/tests/suites/test_suite_bignum_mod.function
index 507920a..4b77a4a 100644
--- a/tests/suites/test_suite_bignum_mod.function
+++ b/tests/suites/test_suite_bignum_mod.function
@@ -203,6 +203,106 @@
     mbedtls_free( X_raw );
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void mpi_mod_inv_mont( char * input_N,
+                       char * input_A, char * input_I,
+                       int expected_ret )
+{
+    mbedtls_mpi_mod_residue a = { NULL, 0 };    /* argument */
+    mbedtls_mpi_mod_residue i = { NULL, 0 };    /* expected inverse wrt N */
+    mbedtls_mpi_mod_residue x = { NULL, 0 };    /* output */
+    mbedtls_mpi_uint *X_raw = NULL;
+
+    mbedtls_mpi_mod_modulus N;
+    mbedtls_mpi_mod_modulus_init( &N );
+
+    TEST_EQUAL( 0,
+        test_read_modulus( &N, MBEDTLS_MPI_MOD_REP_MONTGOMERY, input_N ) );
+
+    /* test_read_residue() normally checks that inputs have the same number of
+     * limbs as the modulus. For negative testing we can ask it to skip this
+     * with a non-zero final parameter. */
+    TEST_EQUAL( 0, test_read_residue( &a, &N, input_A, expected_ret != 0 ) );
+    TEST_EQUAL( 0, test_read_residue( &i, &N, input_I, expected_ret != 0 ) );
+
+    size_t limbs = N.limbs;
+    size_t bytes = limbs * sizeof( *X_raw );
+
+    ASSERT_ALLOC( X_raw, limbs );
+
+    TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &x, &N, X_raw, limbs ) );
+
+    TEST_EQUAL( expected_ret, mbedtls_mpi_mod_inv( &x, &a, &N ) );
+    if( expected_ret == 0 )
+    {
+        TEST_COMPARE_MPI_RESIDUES( x, i );
+
+        /* a^-1: alias x to a => Correct result */
+        memcpy( x.p, a.p, bytes );
+        TEST_EQUAL( 0, mbedtls_mpi_mod_inv( &x, &x, &N ) );
+        TEST_COMPARE_MPI_RESIDUES( x, i );
+    }
+
+exit:
+    mbedtls_free( (void *)N.p ); /* mbedtls_mpi_mod_modulus_free() sets N.p = NULL */
+    mbedtls_mpi_mod_modulus_free( &N );
+
+    mbedtls_free( a.p );
+    mbedtls_free( i.p );
+    mbedtls_free( X_raw );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void mpi_mod_inv_non_mont( char * input_N,
+                           char * input_A, char * input_I,
+                           int expected_ret )
+{
+    mbedtls_mpi_mod_residue a = { NULL, 0 };    /* argument */
+    mbedtls_mpi_mod_residue i = { NULL, 0 };    /* expected inverse wrt N */
+    mbedtls_mpi_mod_residue x = { NULL, 0 };    /* output */
+    mbedtls_mpi_uint *X_raw = NULL;
+
+    mbedtls_mpi_mod_modulus N;
+    mbedtls_mpi_mod_modulus_init( &N );
+
+    TEST_EQUAL( 0,
+        test_read_modulus( &N, MBEDTLS_MPI_MOD_REP_OPT_RED, input_N ) );
+
+    /* test_read_residue() normally checks that inputs have the same number of
+     * limbs as the modulus. For negative testing we can ask it to skip this
+     * with a non-zero final parameter. */
+    TEST_EQUAL( 0, test_read_residue( &a, &N, input_A, expected_ret != 0 ) );
+    TEST_EQUAL( 0, test_read_residue( &i, &N, input_I, expected_ret != 0 ) );
+
+    size_t limbs = N.limbs;
+    size_t bytes = limbs * sizeof( *X_raw );
+
+    ASSERT_ALLOC( X_raw, limbs );
+
+    TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &x, &N, X_raw, limbs ) );
+
+    TEST_EQUAL( expected_ret, mbedtls_mpi_mod_inv( &x, &a, &N ) );
+    if( expected_ret == 0 )
+    {
+        TEST_COMPARE_MPI_RESIDUES( x, i );
+
+        /* a^-1: alias x to a => Correct result */
+        memcpy( x.p, a.p, bytes );
+        TEST_EQUAL( 0, mbedtls_mpi_mod_inv( &x, &x, &N ) );
+        TEST_COMPARE_MPI_RESIDUES( x, i );
+    }
+
+exit:
+    mbedtls_free( (void *)N.p ); /* mbedtls_mpi_mod_modulus_free() sets N.p = NULL */
+    mbedtls_mpi_mod_modulus_free( &N );
+
+    mbedtls_free( a.p );
+    mbedtls_free( i.p );
+    mbedtls_free( X_raw );
+}
+/* END_CASE */
 /* END MERGE SLOT 3 */
 
 /* BEGIN MERGE SLOT 4 */
diff --git a/tests/suites/test_suite_bignum_mod.misc.data b/tests/suites/test_suite_bignum_mod.misc.data
index 7b1c85f..6240e21 100644
--- a/tests/suites/test_suite_bignum_mod.misc.data
+++ b/tests/suites/test_suite_bignum_mod.misc.data
@@ -38,6 +38,50 @@
 mpi_mod_sub with second input too short
 mpi_mod_sub:"014320a022ccb75bdf470ddf25":"000000025a55a46e5da99c71c7":"e8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
 
+mbedtls_mpi_mod_inv non-Mont. form - base case for negative testing (N, A, A^-1)
+mpi_mod_inv_non_mont:"000000000000152d02c7e14af67fe0bf":"00000000000000000000000000000038":"000000000000097418193b6f2e0b5fc3":0
+
+mbedtls_mpi_mod_inv non-Mont. form - A == 0
+mpi_mod_inv_non_mont:"000000000000152d02c7e14af67fe0bf":"00000000000000000000000000000000":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv non-Mont. form - A too long
+mpi_mod_inv_non_mont:"000000000000152d02c7e14af67fe0bf":"0000000000000000000000000000000000000038":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv non-Mont. form - A too short
+mpi_mod_inv_non_mont:"000000000000152d02c7e14af67fe0bf":"0000000000000038":"000000000000097418193b6f2e0b5fc3":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv 32-bit Mont. form - base case for negative testing, A = 1 (N, mont(A), mont(A^-1))
+depends_on:MBEDTLS_HAVE_INT32
+mpi_mod_inv_mont:"000000000000152d02c7e14af67fe0bf":"0000000000000d71d51539b9c02b7b28":"0000000000000d71d51539b9c02b7b28":0
+
+mbedtls_mpi_mod_inv 32-bit Mont. form - A == 0
+depends_on:MBEDTLS_HAVE_INT32
+mpi_mod_inv_mont:"000000000000152d02c7e14af67fe0bf":"00000000000000000000000000000000":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv 32-bit Mont. form - A too long
+depends_on:MBEDTLS_HAVE_INT32
+mpi_mod_inv_mont:"000000000000152d02c7e14af67fe0bf":"000000000000000000000d71d51539b9c02b7b28":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv 32-bit Mont. form - A too short
+depends_on:MBEDTLS_HAVE_INT32
+mpi_mod_inv_mont:"000000000000152d02c7e14af67fe0bf":"00000d71d51539b9c02b7b28":"0000000000000d71d51539b9c02b7b28":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv 64-bit Mont. form - base case for negative testing, A = 1 (N, mont(A), mont(A^-1))
+depends_on:MBEDTLS_HAVE_INT64
+mpi_mod_inv_mont:"0000000000000000000000000000152d02c7e14af67fe0bf":"000000000000000000000000000009545642424381c611fb":"000000000000000000000000000009545642424381c611fb":0
+
+mbedtls_mpi_mod_inv 64-bit Mont. form - A == 0
+depends_on:MBEDTLS_HAVE_INT64
+mpi_mod_inv_mont:"0000000000000000000000000000152d02c7e14af67fe0bf":"000000000000000000000000000000000000000000000000":"000000000000000000000000000009545642424381c611fb":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv 64-bit Mont. form - A too long
+depends_on:MBEDTLS_HAVE_INT64
+mpi_mod_inv_mont:"0000000000000000000000000000152d02c7e14af67fe0bf":"0000000000000000000000000000000000000000000009545642424381c611fb":"000000000000000000000000000009545642424381c611fb":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+mbedtls_mpi_mod_inv 64-bit Mont. form - A too short
+depends_on:MBEDTLS_HAVE_INT64
+mpi_mod_inv_mont:"0000000000000000000000000000152d02c7e14af67fe0bf":"00000000000009545642424381c611fb":"000000000000000000000000000009545642424381c611fb":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
 # END MERGE SLOT 3
 
 # BEGIN MERGE SLOT 4