diff --git a/stages/org.osbuild.bootupd b/stages/org.osbuild.bootupd
index 22da890d..b4d96828 100755
--- a/stages/org.osbuild.bootupd
+++ b/stages/org.osbuild.bootupd
@@ -9,6 +9,7 @@ and GRUB for BIOS firmware on x86_64.
 The project is deployed in Fedora CoreOS and derivatives
 """
 
+import contextlib
 import os
 import subprocess
 import sys
@@ -67,6 +68,19 @@ SCHEMA_2 = r"""
 """
 
 
+@contextlib.contextmanager
+def bind_mounts(sources, dest_root):
+    for src in sources:
+        dst = os.path.join(dest_root, src.lstrip("/"))
+        subprocess.run(["mount", "--rbind", src, dst], check=True)
+    try:
+        yield
+    finally:
+        for src in sources:
+            dst = os.path.join(dest_root, src.lstrip("/"))
+            subprocess.run(["umount", "--recursive", dst], check=False)
+
+
 def main(args, options):
     deployment = options.get("deployment", None)
     static_configs = options.get("static-configs", False)
@@ -101,22 +115,11 @@ def main(args, options):
     # want to make sure the version used matches the target and not
     # risk any inconsistencies with the build root). Let's set up
     # and chroot to run the bootupctl command from the target.
-    submounts = ['dev', 'proc', 'sys', 'run', 'var', 'tmp']
-    for mnt in submounts:
-        subprocess.run(['mount', '--rbind',
-                       os.path.join("/", mnt),
-                       os.path.join(root, mnt)],
-                       check=True)
-    try:
+    with bind_mounts(['/dev', '/proc', '/sys', '/run', '/var', '/tmp'], root):
         cmd = ['chroot', root, '/usr/bin/bootupctl', 'backend', 'install']
         cmd.extend(bootupd_args)
         cmd.append(mounts)
         subprocess.run(cmd, check=True)
-    finally:
-        for mnt in submounts:
-            subprocess.run(['umount', '--recursive',
-                           os.path.join(root, mnt)],
-                           check=False)
 
     return 0
 
diff --git a/stages/test/test_bootupd.py b/stages/test/test_bootupd.py
index d7d2423e..e35a1d84 100644
--- a/stages/test/test_bootupd.py
+++ b/stages/test/test_bootupd.py
@@ -1,39 +1,42 @@
 #!/usr/bin/python3
 
 import os.path
-import subprocess
-from unittest import mock
+from unittest.mock import call, patch
 
 import pytest
 
 import osbuild.meta
-from osbuild.testutil import has_executable, make_fake_input_tree
 from osbuild.testutil.imports import import_module_from_path
 
 
 @pytest.mark.parametrize("test_data,expected_err", [
     # bad
-    ({"deployment": "totally"}, "'totally' is not of type 'object'"),
+    ({"deployment": "must-be-object"}, "'must-be-object' is not of type 'object'"),
     ({"deployment": {"osname": "some-os"}}, "'ref' is a required property"),
     ({"deployment": {"ref": "some-ref"}}, "'osname' is a required property"),
-    ({"deployment": {"osname": "some-os", "ref": "some-ref", "serial": "yo"}}, "'yo' is not of type 'number'"),
+    ({"deployment": {"osname": "some-os", "ref": "some-ref", "serial": "must-be-number"}},
+     "'must-be-number' is not of type 'number'"),
     ({"random": "property"}, "Additional properties are not allowed"),
     ({"bios": {}}, "'device' is a required property"),
-    ({"bios": "yes"}, "'yes' is not of type 'object'"),
+    ({"bios": "must-be-object"}, "'must-be-object' is not of type 'object'"),
     # good
     ({}, ""),
-    ({"deployment": {
-          "osname": "some-os",
-          "ref": "some-ref",
-          "serial": 1,
-      },
-      "static-configs": True,
-      "bios": {
-          "device": "/dev/sda",
-      }}, "")
+    ({
+        "deployment":
+        {
+            "osname": "some-os",
+            "ref": "some-ref",
+            "serial": 1,
+        },
+        "static-configs": True,
+        "bios":
+        {
+            "device": "/dev/sda",
+        },
+    }, "")
 
 ])
-def test_schema_validation_bootupd(test_data, expected_err):
+def test_bootupd_schema_validation(test_data, expected_err):
     name = "org.osbuild.bootupd"
     root = os.path.join(os.path.dirname(__file__), "../..")
     mod_info = osbuild.meta.ModuleInfo.load(root, "Stage", name)
@@ -54,3 +57,33 @@ def test_schema_validation_bootupd(test_data, expected_err):
         assert len(res.errors) == 1, [e.as_dict() for e in res.errors]
         err_msgs = [e.as_dict()["message"] for e in res.errors]
         assert expected_err in err_msgs[0]
+
+
+@patch("subprocess.run")
+def test_bootupd_defaults(mocked_run):
+    stage_path = os.path.join(os.path.dirname(__file__), "../org.osbuild.bootupd")
+    stage = import_module_from_path("bootupd_stage", stage_path)
+
+    args = {
+        "paths": {
+            "mounts": "/run/osbuild/mounts",
+        },
+    }
+    options = {}
+    stage.main(args, options)
+
+    assert mocked_run.call_args_list == [
+        call(["mount", "--rbind", "/dev", "/run/osbuild/mounts/dev"], check=True),
+        call(["mount", "--rbind", "/proc", "/run/osbuild/mounts/proc"], check=True),
+        call(["mount", "--rbind", "/sys", "/run/osbuild/mounts/sys"], check=True),
+        call(["mount", "--rbind", "/run", "/run/osbuild/mounts/run"], check=True),
+        call(["mount", "--rbind", "/var", "/run/osbuild/mounts/var"], check=True),
+        call(["mount", "--rbind", "/tmp", "/run/osbuild/mounts/tmp"], check=True),
+        call(["chroot", "/run/osbuild/mounts", "/usr/bin/bootupctl", "backend", "install", "/run/osbuild/mounts"], check=True),
+        call(["umount", "--recursive", "/run/osbuild/mounts/dev"], check=False),
+        call(["umount", "--recursive", "/run/osbuild/mounts/proc"], check=False),
+        call(["umount", "--recursive", "/run/osbuild/mounts/sys"], check=False),
+        call(["umount", "--recursive", "/run/osbuild/mounts/run"], check=False),
+        call(["umount", "--recursive", "/run/osbuild/mounts/var"], check=False),
+        call(["umount", "--recursive", "/run/osbuild/mounts/tmp"], check=False),
+    ]