diff --git a/tests/suites/test_suite_rsa.function b/tests/suites/test_suite_rsa.function
index 60c13c8..b004c95 100644
--- a/tests/suites/test_suite_rsa.function
+++ b/tests/suites/test_suite_rsa.function
@@ -275,6 +275,12 @@
                                                     valid_mode,
                                                     0, sizeof( buf ), buf,
                                                     NULL ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_RSA_BAD_INPUT_DATA,
+                            mbedtls_rsa_pkcs1_sign( &ctx, NULL, NULL,
+                                                    valid_mode,
+                                                    MBEDTLS_MD_SHA1,
+                                                    0, NULL,
+                                                    buf ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_RSA_BAD_INPUT_DATA,
                             mbedtls_rsa_rsassa_pkcs1_v15_sign( NULL, NULL, NULL,