diff --git a/meson.build b/meson.build
index 800b70f1..faf51b87 100644
--- a/meson.build
+++ b/meson.build
@@ -52,9 +52,9 @@ valac = meson.get_compiler('vala')
 # Required libraries and other dependencies
 #
 
-target_glib = '2.68'
+target_glib = '2.74'
 target_gtk = '3.24.24'
-target_vala = '0.48.18'
+target_vala = '0.56'
 target_webkit = '2.30'
 
 if not valac.version().version_compare('>=' + target_vala)
diff --git a/src/client/plugin/mail-merge/mail-merge-test.vala b/src/client/plugin/mail-merge/mail-merge-test.vala
index 39cc6d10..fac6435d 100644
--- a/src/client/plugin/mail-merge/mail-merge-test.vala
+++ b/src/client/plugin/mail-merge/mail-merge-test.vala
@@ -17,8 +17,8 @@ int main(string[] args) {
     }
 
     GLib.TestSuite root = GLib.TestSuite.get_root();
-    root.add_suite(new MailMerge.TestReader().suite);
-    root.add_suite(new MailMerge.TestProcessor().suite);
+    root.add_suite(new MailMerge.TestReader().steal_suite());
+    root.add_suite(new MailMerge.TestProcessor().steal_suite());
 
     GLib.MainLoop loop = new GLib.MainLoop();
     int ret = -1;
diff --git a/subprojects/vala-unit/meson.build b/subprojects/vala-unit/meson.build
index eb1975b3..f3160d5d 100644
--- a/subprojects/vala-unit/meson.build
+++ b/subprojects/vala-unit/meson.build
@@ -1,7 +1,7 @@
 project(
   'vala-unit',
   [ 'vala', 'c' ],
-  version: '1.0',
+  version: '2.0',
   license: 'LGPL2.1+',
   meson_version: '>= 0.50',
 )
@@ -20,8 +20,8 @@ add_project_arguments(
   language: 'vala'
 )
 
-target_vala = '0.44'
-target_glib = '2.62'
+target_vala = '0.56'
+target_glib = '2.74'
 
 if not meson.get_compiler('vala').version().version_compare('>=' + target_vala)
   error('Vala does not meet minimum required version: ' + target_vala)
@@ -61,7 +61,7 @@ test_sources = files(
 )
 
 package_name = 'ValaUnit'
-package_version = '1.0'
+package_version = '2.0'
 package_full = '@0@-@1@'.format(package_name, package_version)
 package_vapi = '@0@-@1@'.format(meson.project_name(), package_version)
 package_gir = package_full + '.gir'
diff --git a/subprojects/vala-unit/src/test-case.vala b/subprojects/vala-unit/src/test-case.vala
index 9a7fc888..db4e9dbd 100644
--- a/subprojects/vala-unit/src/test-case.vala
+++ b/subprojects/vala-unit/src/test-case.vala
@@ -46,7 +46,7 @@ public abstract class ValaUnit.TestCase : GLib.Object, TestAssertions {
     public string name { get; private set; }
 
     /** The collection of GLib tests defined by this test case. */
-    public GLib.TestSuite suite { get; private set; }
+    protected GLib.TestSuite suite;
 
     /** Main loop context for this test case. */
     protected GLib.MainContext main_loop {
@@ -204,4 +204,13 @@ public abstract class ValaUnit.TestCase : GLib.Object, TestAssertions {
         );
     }
 
+    /**
+     * Steals the {@link GLib.TestSuite} that this test case wraps.
+     *
+     * After this method, you should *no longer* use this object!
+     */
+    public GLib.TestSuite steal_suite() {
+        return (owned) this.suite;
+    }
+
 }
diff --git a/subprojects/vala-unit/test/test-driver.vala b/subprojects/vala-unit/test/test-driver.vala
index 9b6f3698..5b195782 100644
--- a/subprojects/vala-unit/test/test-driver.vala
+++ b/subprojects/vala-unit/test/test-driver.vala
@@ -8,9 +8,9 @@
 int main(string[] args) {
     Test.init(ref args);
 
-    TestSuite root = TestSuite.get_root();
-    root.add_suite(new TestAssertions().suite);
-    root.add_suite(new CollectionAssertions().suite);
+    unowned TestSuite root = TestSuite.get_root();
+    root.add_suite(new TestAssertions().steal_suite());
+    root.add_suite(new CollectionAssertions().steal_suite());
 
     MainLoop loop = new MainLoop ();
 
diff --git a/test/meson.build b/test/meson.build
index 17903a65..7bf5211f 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -126,6 +126,7 @@ test_integration_sources = [
 
 test_engine_dependencies = [
   config_dep,
+  glib,
   engine_internal_dep,
   vala_unit_dep,
 ]
@@ -151,6 +152,7 @@ test_engine_bin = executable('test-engine',
 
 test_client_dependencies = [
   config_dep,
+  glib,
   client_internal_dep,
   vala_unit_dep,
 ]
@@ -166,6 +168,7 @@ test_client_bin = executable('test-client',
 
 test_js_dependencies = [
   config_dep,
+  glib,
   client_internal_dep,
   vala_unit_dep,
 ]
@@ -185,6 +188,7 @@ test_integration_bin = executable('test-integration',
   test_integration_sources,
   dependencies: [
     config_dep,
+    glib,
     engine_dep,
     gee,
     gio,
diff --git a/test/test-client.vala b/test/test-client.vala
index 66b60665..b3685e9b 100644
--- a/test/test-client.vala
+++ b/test/test-client.vala
@@ -44,23 +44,23 @@ int main(string[] args) {
 
     // Keep this before other ClientWebView based tests since it tests
     // WebContext init
-    client.add_suite(new Accounts.ManagerTest().suite);
-    client.add_suite(new Application.CertificateManagerTest().suite);
-    client.add_suite(new Application.ClientTest().suite);
-    client.add_suite(new Application.ConfigurationTest().suite);
-    client.add_suite(new Components.WebViewTest().suite);
-    client.add_suite(new Components.ValidatorTest().suite);
-    client.add_suite(new Composer.WebViewTest().suite);
-    client.add_suite(new Composer.WidgetTest().suite);
-    client.add_suite(new Util.Cache.Test().suite);
-    client.add_suite(new Util.Email.Test().suite);
-    client.add_suite(new Util.JS.Test().suite);
+    client.add_suite(new Accounts.ManagerTest().steal_suite());
+    client.add_suite(new Application.CertificateManagerTest().steal_suite());
+    client.add_suite(new Application.ClientTest().steal_suite());
+    client.add_suite(new Application.ConfigurationTest().steal_suite());
+    client.add_suite(new Components.WebViewTest().steal_suite());
+    client.add_suite(new Components.ValidatorTest().steal_suite());
+    client.add_suite(new Composer.WebViewTest().steal_suite());
+    client.add_suite(new Composer.WidgetTest().steal_suite());
+    client.add_suite(new Util.Cache.Test().steal_suite());
+    client.add_suite(new Util.Email.Test().steal_suite());
+    client.add_suite(new Util.JS.Test().steal_suite());
 
     /*
      * Run the tests
      */
-    TestSuite root = TestSuite.get_root();
-    root.add_suite(client);
+    unowned TestSuite root = TestSuite.get_root();
+    root.add_suite((owned) client);
 
     int ret = -1;
     Idle.add(() => {
diff --git a/test/test-engine.vala b/test/test-engine.vala
index 699683b6..1a097562 100644
--- a/test/test-engine.vala
+++ b/test/test-engine.vala
@@ -28,75 +28,75 @@ int main(string[] args) {
 
     TestSuite engine = new TestSuite("engine");
 
-    engine.add_suite(new Geary.AccountInformationTest().suite);
-    engine.add_suite(new Geary.AttachmentTest().suite);
-    engine.add_suite(new Geary.ContactHarvesterImplTest().suite);
-    engine.add_suite(new Geary.EngineTest().suite);
-    engine.add_suite(new Geary.FolderPathTest().suite);
-    engine.add_suite(new Geary.IdleManagerTest().suite);
-    engine.add_suite(new Geary.TimeoutManagerTest().suite);
-    engine.add_suite(new Geary.TlsNegotiationMethodTest().suite);
-    engine.add_suite(new Geary.App.ConversationTest().suite);
-    engine.add_suite(new Geary.App.ConversationSetTest().suite);
+    engine.add_suite(new Geary.AccountInformationTest().steal_suite());
+    engine.add_suite(new Geary.AttachmentTest().steal_suite());
+    engine.add_suite(new Geary.ContactHarvesterImplTest().steal_suite());
+    engine.add_suite(new Geary.EngineTest().steal_suite());
+    engine.add_suite(new Geary.FolderPathTest().steal_suite());
+    engine.add_suite(new Geary.IdleManagerTest().steal_suite());
+    engine.add_suite(new Geary.TimeoutManagerTest().steal_suite());
+    engine.add_suite(new Geary.TlsNegotiationMethodTest().steal_suite());
+    engine.add_suite(new Geary.App.ConversationTest().steal_suite());
+    engine.add_suite(new Geary.App.ConversationSetTest().steal_suite());
     // Depends on ConversationTest and ConversationSetTest passing
-    engine.add_suite(new Geary.App.ConversationMonitorTest().suite);
-    engine.add_suite(new Geary.Ascii.Test().suite);
-    engine.add_suite(new Geary.ConfigFileTest().suite);
-    engine.add_suite(new Geary.Db.DatabaseTest().suite);
-    engine.add_suite(new Geary.Db.VersionedDatabaseTest().suite);
-    engine.add_suite(new Geary.HTML.UtilTest().suite);
+    engine.add_suite(new Geary.App.ConversationMonitorTest().steal_suite());
+    engine.add_suite(new Geary.Ascii.Test().steal_suite());
+    engine.add_suite(new Geary.ConfigFileTest().steal_suite());
+    engine.add_suite(new Geary.Db.DatabaseTest().steal_suite());
+    engine.add_suite(new Geary.Db.VersionedDatabaseTest().steal_suite());
+    engine.add_suite(new Geary.HTML.UtilTest().steal_suite());
 
     // Other IMAP tests rely on these working, so test them first
-    engine.add_suite(new Geary.Imap.DataFormatTest().suite);
+    engine.add_suite(new Geary.Imap.DataFormatTest().steal_suite());
 
-    engine.add_suite(new Geary.Imap.CreateCommandTest().suite);
-    engine.add_suite(new Geary.Imap.FetchCommandTest().suite);
-    engine.add_suite(new Geary.Imap.FetchDataDecoderTest().suite);
-    engine.add_suite(new Geary.Imap.ListParameterTest().suite);
-    engine.add_suite(new Geary.Imap.MailboxSpecifierTest().suite);
-    engine.add_suite(new Geary.Imap.NamespaceResponseTest().suite);
+    engine.add_suite(new Geary.Imap.CreateCommandTest().steal_suite());
+    engine.add_suite(new Geary.Imap.FetchCommandTest().steal_suite());
+    engine.add_suite(new Geary.Imap.FetchDataDecoderTest().steal_suite());
+    engine.add_suite(new Geary.Imap.ListParameterTest().steal_suite());
+    engine.add_suite(new Geary.Imap.MailboxSpecifierTest().steal_suite());
+    engine.add_suite(new Geary.Imap.NamespaceResponseTest().steal_suite());
 
     // Depends on IMAP commands working
-    engine.add_suite(new Geary.Imap.DeserializerTest().suite);
-    engine.add_suite(new Geary.Imap.ClientConnectionTest().suite);
-    engine.add_suite(new Geary.Imap.ClientSessionTest().suite);
+    engine.add_suite(new Geary.Imap.DeserializerTest().steal_suite());
+    engine.add_suite(new Geary.Imap.ClientConnectionTest().steal_suite());
+    engine.add_suite(new Geary.Imap.ClientSessionTest().steal_suite());
 
-    engine.add_suite(new Geary.ImapDB.AccountTest().suite);
-    engine.add_suite(new Geary.ImapDB.AttachmentTest().suite);
-    engine.add_suite(new Geary.ImapDB.AttachmentIoTest().suite);
-    engine.add_suite(new Geary.ImapDB.DatabaseTest().suite);
-    engine.add_suite(new Geary.ImapDB.EmailIdentifierTest().suite);
-    engine.add_suite(new Geary.ImapDB.FolderTest().suite);
+    engine.add_suite(new Geary.ImapDB.AccountTest().steal_suite());
+    engine.add_suite(new Geary.ImapDB.AttachmentTest().steal_suite());
+    engine.add_suite(new Geary.ImapDB.AttachmentIoTest().steal_suite());
+    engine.add_suite(new Geary.ImapDB.DatabaseTest().steal_suite());
+    engine.add_suite(new Geary.ImapDB.EmailIdentifierTest().steal_suite());
+    engine.add_suite(new Geary.ImapDB.FolderTest().steal_suite());
 
     // Depends on ImapDB working
-    engine.add_suite(new Geary.FtsSearchQueryTest().suite);
+    engine.add_suite(new Geary.FtsSearchQueryTest().steal_suite());
 
-    engine.add_suite(new Geary.ImapEngine.AccountProcessorTest().suite);
-    engine.add_suite(new Geary.ImapEngine.GenericAccountTest().suite);
+    engine.add_suite(new Geary.ImapEngine.AccountProcessorTest().steal_suite());
+    engine.add_suite(new Geary.ImapEngine.GenericAccountTest().steal_suite());
 
     // Depends on ImapDb.Database working correctly
-    engine.add_suite(new Geary.ContactStoreImplTest().suite);
+    engine.add_suite(new Geary.ContactStoreImplTest().steal_suite());
 
-    engine.add_suite(new Geary.Inet.Test().suite);
-    engine.add_suite(new Geary.Mime.ContentTypeTest().suite);
-    engine.add_suite(new Geary.Outbox.EmailIdentifierTest().suite);
-    engine.add_suite(new Geary.RFC822.MailboxAddressTest().suite);
-    engine.add_suite(new Geary.RFC822.MailboxAddressesTest().suite);
-    engine.add_suite(new Geary.RFC822.MessageDataTest().suite);
-    engine.add_suite(new Geary.RFC822.PartTest().suite);
-    engine.add_suite(new Geary.RFC822.Utils.Test().suite);
+    engine.add_suite(new Geary.Inet.Test().steal_suite());
+    engine.add_suite(new Geary.Mime.ContentTypeTest().steal_suite());
+    engine.add_suite(new Geary.Outbox.EmailIdentifierTest().steal_suite());
+    engine.add_suite(new Geary.RFC822.MailboxAddressTest().steal_suite());
+    engine.add_suite(new Geary.RFC822.MailboxAddressesTest().steal_suite());
+    engine.add_suite(new Geary.RFC822.MessageDataTest().steal_suite());
+    engine.add_suite(new Geary.RFC822.PartTest().steal_suite());
+    engine.add_suite(new Geary.RFC822.Utils.Test().steal_suite());
     // Message requires all of the rest of the package working, so put
     // last
-    engine.add_suite(new Geary.RFC822.MessageTest().suite);
-    engine.add_suite(new Geary.String.Test().suite);
-    engine.add_suite(new Geary.EmailTest().suite);
-    engine.add_suite(new Geary.ComposedEmailTest().suite);
+    engine.add_suite(new Geary.RFC822.MessageTest().steal_suite());
+    engine.add_suite(new Geary.String.Test().steal_suite());
+    engine.add_suite(new Geary.EmailTest().steal_suite());
+    engine.add_suite(new Geary.ComposedEmailTest().steal_suite());
 
     /*
      * Run the tests
      */
-    TestSuite root = TestSuite.get_root();
-    root.add_suite(engine);
+    unowned TestSuite root = TestSuite.get_root();
+    root.add_suite((owned) engine);
 
     MainLoop loop = new MainLoop ();
 
diff --git a/test/test-integration.vala b/test/test-integration.vala
index 43254714..8785d7ae 100644
--- a/test/test-integration.vala
+++ b/test/test-integration.vala
@@ -48,19 +48,19 @@ int main(string[] args) {
 
     switch (config.type) {
     case IMAP:
-        integration.add_suite(new Integration.Imap.ClientSession(config).suite);
+        integration.add_suite(new Integration.Imap.ClientSession(config).steal_suite());
         break;
 
     case SMTP:
-        integration.add_suite(new Integration.Smtp.ClientSession(config).suite);
+        integration.add_suite(new Integration.Smtp.ClientSession(config).steal_suite());
         break;
     }
 
     /*
      * Run the tests
      */
-    TestSuite root = TestSuite.get_root();
-    root.add_suite(integration);
+    unowned TestSuite root = TestSuite.get_root();
+    root.add_suite((owned) integration);
 
     MainLoop loop = new MainLoop();
 
@@ -111,4 +111,4 @@ private Integration.Configuration load_config(string[] args) {
         );
     }
 
-}
\ No newline at end of file
+}
diff --git a/test/test-js.vala b/test/test-js.vala
index 7aa4fb1a..c3e0a7d4 100644
--- a/test/test-js.vala
+++ b/test/test-js.vala
@@ -42,15 +42,15 @@ int main(string[] args) {
 
     TestSuite js = new TestSuite("js");
 
-    js.add_suite(new Components.PageStateTest().suite);
-    js.add_suite(new Composer.PageStateTest().suite);
-    js.add_suite(new ConversationPageStateTest().suite);
+    js.add_suite(new Components.PageStateTest().steal_suite());
+    js.add_suite(new Composer.PageStateTest().steal_suite());
+    js.add_suite(new ConversationPageStateTest().steal_suite());
 
     /*
      * Run the tests
      */
-    TestSuite root = TestSuite.get_root();
-    root.add_suite(js);
+    unowned TestSuite root = TestSuite.get_root();
+    root.add_suite((owned) js);
 
     int ret = -1;
     Idle.add(() => {