diff --git a/gio/tests/tls-certificate.c b/gio/tests/tls-certificate.c
index db2511f59..39e9c77df 100644
--- a/gio/tests/tls-certificate.c
+++ b/gio/tests/tls-certificate.c
@@ -44,12 +44,12 @@ pem_parser (const Reference *ref)
   /* Check PEM parsing in certificate, private key order. */
   g_file_get_contents (g_test_get_filename (G_TEST_DIST, "cert-tests", "cert-key.pem", NULL), &pem, &pem_len, &error);
   g_assert_no_error (error);
-  g_assert (pem);
+  g_assert_nonnull (pem);
   g_assert_cmpuint (pem_len, >=, 10);
 
   cert = g_tls_certificate_new_from_pem (pem, -1, &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -79,11 +79,11 @@ pem_parser (const Reference *ref)
   /* Check PEM parsing in private key, certificate order */
   g_file_get_contents (g_test_get_filename (G_TEST_DIST, "cert-tests", "key-cert.pem", NULL), &pem, NULL, &error);
   g_assert_no_error (error);
-  g_assert (pem);
+  g_assert_nonnull (pem);
 
   cert = g_tls_certificate_new_from_pem (pem, -1, &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -101,11 +101,11 @@ pem_parser (const Reference *ref)
   /* Check certificate only PEM */
   g_file_get_contents (g_test_get_filename (G_TEST_DIST, "cert-tests", "cert1.pem", NULL), &pem, NULL, &error);
   g_assert_no_error (error);
-  g_assert (pem);
+  g_assert_nonnull (pem);
 
   cert = g_tls_certificate_new_from_pem (pem, -1, &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -114,7 +114,7 @@ pem_parser (const Reference *ref)
   g_assert_cmpstr (parsed_cert_pem, ==, ref->cert_pems[0]);
   g_free (parsed_cert_pem);
   parsed_cert_pem = NULL;
-  g_assert (parsed_key_pem == NULL);
+  g_assert_null (parsed_key_pem);
 
   g_free (pem);
   g_object_unref (cert);
@@ -122,12 +122,12 @@ pem_parser (const Reference *ref)
   /* Check error with private key only PEM */
   g_file_get_contents (g_test_get_filename (G_TEST_DIST, "cert-tests", "key.pem", NULL), &pem, NULL, &error);
   g_assert_no_error (error);
-  g_assert (pem);
+  g_assert_nonnull (pem);
 
   cert = g_tls_certificate_new_from_pem (pem, -1, &error);
   g_assert_error (error, G_TLS_ERROR, G_TLS_ERROR_BAD_CERTIFICATE);
   g_clear_error (&error);
-  g_assert (cert == NULL);
+  g_assert_null (cert);
   g_free (pem);
 }
 
@@ -145,12 +145,12 @@ pem_parser_handles_chain (const Reference *ref)
   /* Check that a chain with exactly three certificates is returned */
   g_file_get_contents (g_test_get_filename (G_TEST_DIST, "cert-tests", "cert-list.pem", NULL), &pem, NULL, &error);
   g_assert_no_error (error);
-  g_assert (pem);
+  g_assert_nonnull (pem);
 
   cert = original_cert = g_tls_certificate_new_from_pem (pem, -1, &error);
   g_free (pem);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -165,11 +165,11 @@ pem_parser_handles_chain (const Reference *ref)
 
   /* Now test the second cert */
   issuer = g_tls_certificate_get_issuer (cert);
-  g_assert (issuer);
+  g_assert_nonnull (issuer);
 
   cert = issuer;
   issuer = g_tls_certificate_get_issuer (cert);
-  g_assert (issuer);
+  g_assert_nonnull (issuer);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -179,12 +179,12 @@ pem_parser_handles_chain (const Reference *ref)
 
   /* Only the first cert should have a private key */
   parsed_key_pem = g_test_tls_connection_get_private_key_pem (cert);
-  g_assert (!parsed_key_pem);
+  g_assert_null (parsed_key_pem);
 
   /* Now test the final cert */
   cert = issuer;
   issuer = g_tls_certificate_get_issuer (cert);
-  g_assert (!issuer);
+  g_assert_null (issuer);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -193,7 +193,7 @@ pem_parser_handles_chain (const Reference *ref)
   g_clear_pointer (&parsed_cert_pem, g_free);
 
   parsed_key_pem = g_test_tls_connection_get_private_key_pem (cert);
-  g_assert (!parsed_key_pem);
+  g_assert_null (parsed_key_pem);
 
   g_object_unref (original_cert);
 }
@@ -209,7 +209,7 @@ from_file (const Reference *ref)
   cert = g_tls_certificate_new_from_file (g_test_get_filename (G_TEST_DIST, "cert-tests", "key-cert.pem", NULL),
                                           &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -236,7 +236,7 @@ from_files (const Reference *ref)
                                            g_test_get_filename (G_TEST_DIST, "cert-tests", "key.pem", NULL),
                                            &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -256,7 +256,7 @@ from_files (const Reference *ref)
                                            &error);
   g_assert_error (error, G_TLS_ERROR, G_TLS_ERROR_BAD_CERTIFICATE);
   g_clear_error (&error);
-  g_assert (cert == NULL);
+  g_assert_null (cert);
 
   /* Missing certificate */
   cert = g_tls_certificate_new_from_files (g_test_get_filename (G_TEST_DIST, "cert-tests", "key.pem", NULL),
@@ -264,7 +264,7 @@ from_files (const Reference *ref)
                                            &error);
   g_assert_error (error, G_TLS_ERROR, G_TLS_ERROR_BAD_CERTIFICATE);
   g_clear_error (&error);
-  g_assert (cert == NULL);
+  g_assert_null (cert);
 
   /* Using this method twice with a file containing both private key and
    * certificate as a way to inforce private key presence is a fair use
@@ -273,7 +273,7 @@ from_files (const Reference *ref)
                                            g_test_get_filename (G_TEST_DIST, "cert-tests", "key-cert.pem", NULL),
                                            &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
   g_object_unref (cert);
 }
 
@@ -290,7 +290,7 @@ from_files_pkcs8 (const Reference *ref)
                                            g_test_get_filename (G_TEST_DIST, "cert-tests", "key8.pem", NULL),
                                            &error);
   g_assert_no_error (error);
-  g_assert (cert);
+  g_assert_nonnull (cert);
 
   g_object_get (cert,
       "certificate-pem", &parsed_cert_pem,
@@ -356,27 +356,27 @@ main (int   argc,
   path = g_test_build_filename (G_TEST_DIST, "cert-tests", "cert1.pem", NULL);
   g_file_get_contents (path, &ref.cert_pems[0], NULL, &error);
   g_assert_no_error (error);
-  g_assert (ref.cert_pems[0]);
+  g_assert_nonnull (ref.cert_pems[0]);
   g_free (path);
   path = g_test_build_filename (G_TEST_DIST, "cert-tests", "cert2.pem", NULL);
   g_file_get_contents (path, &ref.cert_pems[1], NULL, &error);
   g_assert_no_error (error);
-  g_assert (ref.cert_pems[1]);
+  g_assert_nonnull (ref.cert_pems[1]);
   g_free (path);
   path = g_test_build_filename (G_TEST_DIST, "cert-tests", "cert3.pem", NULL);
   g_file_get_contents (path, &ref.cert_pems[2], NULL, &error);
   g_assert_no_error (error);
-  g_assert (ref.cert_pems[2]);
+  g_assert_nonnull (ref.cert_pems[2]);
   g_free (path);
   path = g_test_build_filename (G_TEST_DIST, "cert-tests", "key.pem", NULL);
   g_file_get_contents (path, &ref.key_pem, NULL, &error);
   g_assert_no_error (error);
-  g_assert (ref.key_pem);
+  g_assert_nonnull (ref.key_pem);
   g_free (path);
   path = g_test_build_filename (G_TEST_DIST, "cert-tests", "key8.pem", NULL);
   g_file_get_contents (path, &ref.key8_pem, NULL, &error);
   g_assert_no_error (error);
-  g_assert (ref.key8_pem);
+  g_assert_nonnull (ref.key8_pem);
   g_free (path);
 
   g_test_add_data_func ("/tls-certificate/pem-parser",