diff --git a/tests/suites/test_suite_bignum.function b/tests/suites/test_suite_bignum.function
index 4cec0a7..40b23fe 100644
--- a/tests/suites/test_suite_bignum.function
+++ b/tests/suites/test_suite_bignum.function
@@ -959,24 +959,47 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void mpi_mod_int( char * input_X, int input_Y,
-                  int input_A, int div_result )
+void mpi_mod_int( char * input_X, char * input_Y,
+                  char * input_A, int mod_result )
 {
     mbedtls_mpi X;
+    mbedtls_mpi Y;
+    mbedtls_mpi A;
     int res;
     mbedtls_mpi_uint r;
-    mbedtls_mpi_init( &X );
 
-    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
-    res = mbedtls_mpi_mod_int( &r, &X, input_Y );
-    TEST_ASSERT( res == div_result );
+    mbedtls_mpi_init( &X );
+    mbedtls_mpi_init( &Y );
+    mbedtls_mpi_init( &A );
+
+    /* We use MPIs to read Y and A since the test framework limits us to
+     * ints, so we can't have 64-bit values */
+    TEST_EQUAL( mbedtls_test_read_mpi( &X, input_X ), 0 );
+    TEST_EQUAL( mbedtls_test_read_mpi( &Y, input_Y ), 0 );
+    TEST_EQUAL( mbedtls_test_read_mpi( &A, input_A ), 0 );
+
+    TEST_EQUAL( Y.n, 1 );
+    TEST_EQUAL( A.n, 1 );
+
+    /* Convert the MPIs for Y and A to signed mbedtls_mpi_uints */
+    mbedtls_mpi_uint y = Y.p[0];
+    if( Y.s == -1 )
+        y = -y;
+    mbedtls_mpi_uint a = A.p[0];
+    if( A.s == -1 )
+        a = -a;
+
+    res = mbedtls_mpi_mod_int( &r, &X, y );
+    TEST_EQUAL( res, mod_result );
     if( res == 0 )
     {
-        TEST_ASSERT( r == (mbedtls_mpi_uint) input_A );
+        TEST_EQUAL( r, a );
     }
 
 exit:
     mbedtls_mpi_free( &X );
+    mbedtls_mpi_free( &Y );
+    mbedtls_mpi_free( &A );
 }
 /* END_CASE */
 
diff --git a/tests/suites/test_suite_bignum.misc.data b/tests/suites/test_suite_bignum.misc.data
index 29ba4ab..70b4998 100644
--- a/tests/suites/test_suite_bignum.misc.data
+++ b/tests/suites/test_suite_bignum.misc.data
@@ -1205,40 +1205,56 @@
 mpi_mod_mpi:"":"-1":"":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
 Base test mbedtls_mpi_mod_int #1
-mpi_mod_int:"3e8":13:12:0
+mpi_mod_int:"3e8":"d":"c":0
 
 Base test mbedtls_mpi_mod_int #2 (Divide by zero)
-mpi_mod_int:"3e8":0:0:MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
+mpi_mod_int:"3e8":"0":"0":MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
 
 Base test mbedtls_mpi_mod_int #3
-mpi_mod_int:"-3e8":13:1:0
+mpi_mod_int:"-3e8":"d":"1":0
 
 Base test mbedtls_mpi_mod_int #4 (Negative modulo)
-mpi_mod_int:"3e8":-13:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+mpi_mod_int:"3e8":"-d":"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
 Base test mbedtls_mpi_mod_int #5 (Negative modulo)
-mpi_mod_int:"-3e8":-13:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+mpi_mod_int:"-3e8":"-d":"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
 Base test mbedtls_mpi_mod_int #6 (By 1)
-mpi_mod_int:"3e8":1:0:0
+mpi_mod_int:"3e8":"1":"0":0
 
 Base test mbedtls_mpi_mod_int #7 (By 2)
-mpi_mod_int:"3e9":2:1:0
+mpi_mod_int:"3e9":"2":"1":0
 
 Base test mbedtls_mpi_mod_int #8 (By 2)
-mpi_mod_int:"3e8":2:0:0
+mpi_mod_int:"3e8":"2":"0":0
 
 Test mbedtls_mpi_mod_int: 0 (null) % 1
-mpi_mod_int:"":1:0:0
+mpi_mod_int:"":"1":"0":0
 
 Test mbedtls_mpi_mod_int: 0 (null) % 2
-mpi_mod_int:"":2:0:0
+mpi_mod_int:"":"2":"0":0
 
 Test mbedtls_mpi_mod_int: 0 (null) % -1
-mpi_mod_int:"":-1:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+mpi_mod_int:"":"-1":"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
 Test mbedtls_mpi_mod_int: 0 (null) % -2
-mpi_mod_int:"":-2:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+mpi_mod_int:"":"-2":"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+# CURRENTLY FAILS
+#Test mbedtls_mpi_mod_int: 230772460340063000000100500000300000010 % 5178236083361335880 -> 3386266129388798810
+#depends_on:MBEDTLS_HAVE_INT64
+#mpi_mod_int:"AD9D28BF6C4E98FDF156BF0980CEE30A":"47DCCA4847DCCA48":"2EFE6F1A7D28035A":0
+
+Test mbedtls_mpi_mod_mpi: 230772460340063000000100500000300000010 % 5178236083361335880 -> 3386266129388798810
+mpi_mod_mpi:"AD9D28BF6C4E98FDF156BF0980CEE30A":"47DCCA4847DCCA48":"2EFE6F1A7D28035A":0
+
+# CURRENTLY FAILS WHEN MPIS ARE 32-BIT: WHEN FIXED, REMOVE "depends_on" LINE
+Test mbedtls_mpi_mod_int: 230772460340063000000100500000300000010 % 1205652040 -> 3644370
+depends_on:MBEDTLS_HAVE_INT64
+mpi_mod_int:"AD9D28BF6C4E98FDF156BF0980CEE30A":"47DCCA48":"379BD2":0
+
+Test mbedtls_mpi_mod_mpi: 230772460340063000000100500000300000010 % 1205652040 -> 3644370
+mpi_mod_mpi:"AD9D28BF6C4E98FDF156BF0980CEE30A":"47DCCA48":"379BD2":0
 
 Base test mbedtls_mpi_exp_mod #1
 mpi_exp_mod:"17":"d":"1d":"18":0