diff --git a/tools/test_updater.py b/tools/test_updater.py
index 40908583..ac22dcdd 100644
--- a/tools/test_updater.py
+++ b/tools/test_updater.py
@@ -17,6 +17,12 @@ def metadata(build=2):
 
 
 class UpdaterTests(unittest.TestCase):
+    def test_steam_relay_is_part_of_the_update_transaction(self):
+        self.assertIn('steam-relay/skate-steam-relay.exe', u.FILES)
+        self.assertIn('steam-relay/steam_api64.dll', u.FILES)
+        # Metadata is replaced last, after all program components.
+        self.assertEqual(u.FILES[-1], 'release.json')
+
     def test_channels_and_identity(self):
         release = dict(draft=False, published_at='2026-01-01', prerelease=True)
         self.assertFalse(u.eligible(release, 'Stable'))
diff --git a/tools/updater.py b/tools/updater.py
index 3532d633..3b62d8ff 100644
--- a/tools/updater.py
+++ b/tools/updater.py
@@ -17,7 +17,8 @@ import zipfile
 REPO = 'SK8-ENGINE/skate-3-rust-engine'
 API = f'https://api.github.com/repos/{REPO}/releases'
 PACKAGE = 'skate3rust-windows-x64.zip'
-FILES = ('skate3rust.exe', 'support/skate3setup.exe', 'support/skate3update.exe', 'release.json')
+FILES = ('skate3rust.exe', 'support/skate3setup.exe', 'support/skate3update.exe',
+         'steam-relay/skate-steam-relay.exe', 'steam-relay/steam_api64.dll', 'release.json')
 PREFIX = 'skate3rust-windows-x64/'