diff --git a/library/bignum_new.c b/library/bignum_new.c
index 6cbc8678c..04f604923 100644
--- a/library/bignum_new.c
+++ b/library/bignum_new.c
@@ -190,17 +190,13 @@ static int mpi_core_clear( mbedtls_mpi_uint *X,
                            size_t nx,
                            size_t limbs )
 {
-    if( X == NULL )
-        return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
-
-    else if( nx < limbs )
+    if( nx < limbs )
         return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
 
-    else
-    {
+    if( X != NULL )
         memset( X, 0, nx * ciL );
-        return( 0 );
-    }
+
+    return( 0 );
 }
 
 /* Convert a big-endian byte array aligned to the size of mbedtls_mpi_uint
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index 30447a6a3..1974e3fc3 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -82,6 +82,9 @@ mpi_read_write_string:16:"":2:"0":4:0:0
 Test mpi_write_string #10 (Negative hex with odd number of digits)
 mpi_read_write_string:16:"-1":16:"":3:0:MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL
 
+Test mbedtls_mpi_core_io functions with null pointers
+mbedtls_mpi_core_io_null
+
 Test mbedtls_mpi_core_io_be #1 (Buffer and limbs just fit, input limb-aligned)
 mbedtls_mpi_core_io_be:"0941379d00fed1491fe15df284dfde4a142f68aa8d412023195cee66883e6290ffe703f4ea5963bf212713cee46b107c09182b5edcd955adac418bf4918e2889af48e1099d513830cec85c26ac1e158b52620e33ba8692f893efbb2f958b4424":96:12:0:0
 
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index 34710c430..b0d947c9d 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -197,6 +197,37 @@ exit:
 }
 /* END_CASE */
 
+/* BEGIN_CASE */
+void mbedtls_mpi_core_io_null()
+{
+    mbedtls_mpi_uint X = 0;
+    int ret;
+
+    ret = mbedtls_mpi_core_read_be( &X, 1, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+    ret = mbedtls_mpi_core_write_be( &X, 1, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_mpi_core_read_be( NULL, 0, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+    ret = mbedtls_mpi_core_write_be( NULL, 0, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_mpi_core_read_le( &X, 1, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+    ret = mbedtls_mpi_core_write_le( &X, 1, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_mpi_core_read_le( NULL, 0, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+    ret = mbedtls_mpi_core_write_le( NULL, 0, NULL, 0 );
+    TEST_ASSERT( ret == 0 );
+
+exit:
+    ;
+}
+/* END_CASE */
+
 /* BEGIN_CASE */
 void mbedtls_mpi_core_io_be( data_t *input, int nb_int, int nx_64_int, int iret,
                              int oret )