diff --git a/tests/suites/test_suite_chacha20.function b/tests/suites/test_suite_chacha20.function
index 23f6d9e..49b389c 100644
--- a/tests/suites/test_suite_chacha20.function
+++ b/tests/suites/test_suite_chacha20.function
@@ -94,6 +94,7 @@
     mbedtls_chacha20_context ctx;
 
     TEST_INVALID_PARAM( mbedtls_chacha20_init( NULL ) );
+    TEST_VALID_PARAM( mbedtls_chacha20_free( NULL ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA,
                             mbedtls_chacha20_setkey( NULL, key ) );
diff --git a/tests/suites/test_suite_chachapoly.function b/tests/suites/test_suite_chachapoly.function
index 51cc0ab..8e56bf6 100644
--- a/tests/suites/test_suite_chachapoly.function
+++ b/tests/suites/test_suite_chachapoly.function
@@ -139,6 +139,7 @@
     memset( mac,    0x00, sizeof( mac ) );
 
     TEST_INVALID_PARAM( mbedtls_chachapoly_init( NULL ) );
+    TEST_VALID_PARAM( mbedtls_chachapoly_free( NULL ) );
 
     /* setkey */
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA,
diff --git a/tests/suites/test_suite_poly1305.function b/tests/suites/test_suite_poly1305.function
index d4761fb..066bb39 100644
--- a/tests/suites/test_suite_poly1305.function
+++ b/tests/suites/test_suite_poly1305.function
@@ -98,6 +98,7 @@
     mbedtls_poly1305_context ctx;
 
     TEST_INVALID_PARAM( mbedtls_poly1305_init( NULL ) );
+    TEST_VALID_PARAM( mbedtls_poly1305_free( NULL ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA,
                  mbedtls_poly1305_starts( NULL, key ) );