diff --git a/gio/tests/gdbus-addresses.c b/gio/tests/gdbus-addresses.c
index 75ad7e4cd..b7d11d09f 100644
--- a/gio/tests/gdbus-addresses.c
+++ b/gio/tests/gdbus-addresses.c
@@ -209,7 +209,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add_func ("/gdbus/empty-address", test_empty_address);
   g_test_add_func ("/gdbus/unsupported-address", test_unsupported_address);
diff --git a/gio/tests/gdbus-auth.c b/gio/tests/gdbus-auth.c
index e62f53f87..353de5346 100644
--- a/gio/tests/gdbus-auth.c
+++ b/gio/tests/gdbus-auth.c
@@ -287,7 +287,7 @@ main (int   argc,
 
   temp_dbus_keyrings_setup ();
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add_func ("/gdbus/auth/client/EXTERNAL",         auth_client_external);
   g_test_add_func ("/gdbus/auth/client/DBUS_COOKIE_SHA1", auth_client_dbus_cookie_sha1);
diff --git a/gio/tests/gdbus-bz627724.c b/gio/tests/gdbus-bz627724.c
index 62a600013..82d9e80d3 100644
--- a/gio/tests/gdbus-bz627724.c
+++ b/gio/tests/gdbus-bz627724.c
@@ -80,7 +80,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_dbus_unset ();
 
diff --git a/gio/tests/gdbus-close-pending.c b/gio/tests/gdbus-close-pending.c
index f0792ddfc..7d4d6c9ab 100644
--- a/gio/tests/gdbus-close-pending.c
+++ b/gio/tests/gdbus-close-pending.c
@@ -385,7 +385,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add ("/gdbus/close-pending", Fixture, "close",
       setup, test_many_times, teardown);
diff --git a/gio/tests/gdbus-connection-loss.c b/gio/tests/gdbus-connection-loss.c
index 134f15150..b1df43fdb 100644
--- a/gio/tests/gdbus-connection-loss.c
+++ b/gio/tests/gdbus-connection-loss.c
@@ -114,7 +114,7 @@ main (int   argc,
   gint ret;
   gchar *path;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-connection-slow.c b/gio/tests/gdbus-connection-slow.c
index 1d12bb27c..5a3479234 100644
--- a/gio/tests/gdbus-connection-slow.c
+++ b/gio/tests/gdbus-connection-slow.c
@@ -225,7 +225,7 @@ main (int   argc,
 {
   gint ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-connection.c b/gio/tests/gdbus-connection.c
index d04dd0446..05b1f120a 100644
--- a/gio/tests/gdbus-connection.c
+++ b/gio/tests/gdbus-connection.c
@@ -1277,7 +1277,7 @@ main (int   argc,
 {
   int ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-error.c b/gio/tests/gdbus-error.c
index 73f84a9d8..4925b950b 100644
--- a/gio/tests/gdbus-error.c
+++ b/gio/tests/gdbus-error.c
@@ -260,7 +260,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add_func ("/gdbus/registered-errors", test_registered_errors);
   g_test_add_func ("/gdbus/unregistered-errors", test_unregistered_errors);
diff --git a/gio/tests/gdbus-exit-on-close.c b/gio/tests/gdbus-exit-on-close.c
index 916016870..e3aba16a9 100644
--- a/gio/tests/gdbus-exit-on-close.c
+++ b/gio/tests/gdbus-exit-on-close.c
@@ -201,7 +201,7 @@ main (int   argc,
 {
   gint i;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   for (i = 0; cases[i].name != NULL; i++)
     {
diff --git a/gio/tests/gdbus-export.c b/gio/tests/gdbus-export.c
index 5ac53200c..ab8a371f5 100644
--- a/gio/tests/gdbus-export.c
+++ b/gio/tests/gdbus-export.c
@@ -1966,7 +1966,7 @@ main (int   argc,
 {
   gint ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-introspection.c b/gio/tests/gdbus-introspection.c
index 035de5723..44cb7a96a 100644
--- a/gio/tests/gdbus-introspection.c
+++ b/gio/tests/gdbus-introspection.c
@@ -307,7 +307,7 @@ main (int   argc,
 {
   gint ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-message.c b/gio/tests/gdbus-message.c
index 2963405da..647cd7a24 100644
--- a/gio/tests/gdbus-message.c
+++ b/gio/tests/gdbus-message.c
@@ -217,7 +217,7 @@ main (int   argc,
 {
   setlocale (LC_ALL, "C");
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add_func ("/gdbus/message/lock", message_lock);
   g_test_add_func ("/gdbus/message/copy", message_copy);
diff --git a/gio/tests/gdbus-names.c b/gio/tests/gdbus-names.c
index 9487cd65f..c06971097 100644
--- a/gio/tests/gdbus-names.c
+++ b/gio/tests/gdbus-names.c
@@ -1340,7 +1340,7 @@ main (int   argc,
 {
   gint ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_dbus_unset ();
 
diff --git a/gio/tests/gdbus-overflow.c b/gio/tests/gdbus-overflow.c
index b0dc89f0f..45fc109ac 100644
--- a/gio/tests/gdbus-overflow.c
+++ b/gio/tests/gdbus-overflow.c
@@ -209,7 +209,7 @@ main (int   argc,
   GDBusNodeInfo *introspection_data = NULL;
   gchar *tmpdir = NULL;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   introspection_data = g_dbus_node_info_new_for_xml (test_interface_introspection_xml, NULL);
   g_assert (introspection_data != NULL);
diff --git a/gio/tests/gdbus-proxy-threads.c b/gio/tests/gdbus-proxy-threads.c
index a0a38d07c..9cb1a6e22 100644
--- a/gio/tests/gdbus-proxy-threads.c
+++ b/gio/tests/gdbus-proxy-threads.c
@@ -250,7 +250,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_dbus_unset ();
 
diff --git a/gio/tests/gdbus-proxy-unique-name.c b/gio/tests/gdbus-proxy-unique-name.c
index ab39dbc4b..f00010c40 100644
--- a/gio/tests/gdbus-proxy-unique-name.c
+++ b/gio/tests/gdbus-proxy-unique-name.c
@@ -203,7 +203,7 @@ main (int   argc,
 {
   gint ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-proxy-well-known-name.c b/gio/tests/gdbus-proxy-well-known-name.c
index 5a11c1162..990320732 100644
--- a/gio/tests/gdbus-proxy-well-known-name.c
+++ b/gio/tests/gdbus-proxy-well-known-name.c
@@ -260,7 +260,7 @@ main (int   argc,
 {
   gint ret;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* all the tests rely on a shared main loop */
   loop = g_main_loop_new (NULL, FALSE);
diff --git a/gio/tests/gdbus-proxy.c b/gio/tests/gdbus-proxy.c
index 646c5e77c..ac5f720fa 100644
--- a/gio/tests/gdbus-proxy.c
+++ b/gio/tests/gdbus-proxy.c
@@ -1017,7 +1017,7 @@ main (int   argc,
   gint ret;
   GDBusNodeInfo *introspection_data = NULL;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   introspection_data = g_dbus_node_info_new_for_xml (frob_dbus_interface_xml, NULL);
   g_assert_nonnull (introspection_data);
diff --git a/gio/tests/gdbus-serialization.c b/gio/tests/gdbus-serialization.c
index 088152716..8285d1111 100644
--- a/gio/tests/gdbus-serialization.c
+++ b/gio/tests/gdbus-serialization.c
@@ -1624,7 +1624,7 @@ main (int   argc,
   g_setenv ("LC_ALL", "C", TRUE);
   setlocale (LC_ALL, "C");
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add_func ("/gdbus/message-serialize/basic",
                    test_message_serialize_basic);
diff --git a/gio/tests/gdbus-test-codegen.c b/gio/tests/gdbus-test-codegen.c
index 44109f8e5..0a180b8fc 100644
--- a/gio/tests/gdbus-test-codegen.c
+++ b/gio/tests/gdbus-test-codegen.c
@@ -2736,7 +2736,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   g_test_add_func ("/gdbus/codegen/annotations", test_annotations);
   g_test_add_func ("/gdbus/codegen/interface_stability", test_interface_stability);
diff --git a/gio/tests/gdbus-test-fixture.c b/gio/tests/gdbus-test-fixture.c
index 2071bbad9..70f455e19 100644
--- a/gio/tests/gdbus-test-fixture.c
+++ b/gio/tests/gdbus-test-fixture.c
@@ -80,7 +80,7 @@ int
 main (int   argc,
       char *argv[])
 {
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   /* This test simply ensures that we can bring the GTestDBus up and down a hand
    * full of times in a row, each time successfully activating the in-tree service
diff --git a/gio/tests/gdbus-threading.c b/gio/tests/gdbus-threading.c
index 8323dd292..755b490e0 100644
--- a/gio/tests/gdbus-threading.c
+++ b/gio/tests/gdbus-threading.c
@@ -677,7 +677,7 @@ main (int   argc,
   gint ret;
   gchar *path;
 
-  g_test_init (&argc, &argv, NULL);
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
 
   session_bus_up ();