diff --git a/stages/test/test_write_device.py b/stages/test/test_write_device.py
new file mode 100644
index 00000000..53805da5
--- /dev/null
+++ b/stages/test/test_write_device.py
@@ -0,0 +1,89 @@
+#!/usr/bin/python3
+
+import contextlib
+import os
+import struct
+import subprocess
+from unittest.mock import call, mock_open, patch
+
+import pytest  # type: ignore
+
+STAGE_NAME = "org.osbuild.write-device"
+
+
+def create_args(tree):
+    tree.mkdir()
+    a_file = tree / "a-file"
+    a_file.write_text("Some content")
+
+    options = {
+        "from": "input://tree/a-file"
+    }
+    devices = {
+        "device": {
+            "path": "/dev/loop2",
+        },
+    }
+    args = {
+        "inputs": {
+            "tree": {
+                "path": f"{tree}",
+            }
+        },
+        "devices": devices,
+        "options": options,
+    }
+    return args
+
+
+def block_device_size(size):
+    return struct.pack('L', size)
+
+
+@patch("subprocess.run")
+@patch("builtins.open", mock_open(read_data="data"))
+def test_write_device(mocked_run, tmp_path, stage_module):
+    tree = tmp_path / "tree"
+    args = create_args(tree)
+
+    with patch("fcntl.ioctl", return_value=block_device_size(1024)):
+        stage_module.main(args, args["devices"], args["options"])
+
+    assert mocked_run.call_args_list == [
+        call(["dd", f"if={tree}/a-file", "of=/dev/loop2", "status=progress", "conv=fsync"], check=True)]
+
+
+@patch("builtins.open", mock_open(read_data="data"))
+def test_write_device_size_check(tmp_path, stage_module):
+    tree = tmp_path / "tree"
+    args = create_args(tree)
+
+    with pytest.raises(ValueError, match=r"File too large \(0.0 mb\) for device \(0.0 mb\)"):
+        with patch("fcntl.ioctl", return_value=block_device_size(4)):
+            stage_module.main(args, args["devices"], args["options"])
+
+
+@pytest.mark.skipif(os.getuid() != 0, reason="test must run as root")
+def test_write_device_integration(tmp_path, stage_module):
+    tree = tmp_path / "tree"
+    args = create_args(tree)
+    # ensure we have a ramdisk
+    subprocess.check_call(["modprobe", "brd"])
+    test_blk_device = "/dev/ram7"
+    if open(test_blk_device, "br").read(512) != b'\x00' * 512:
+        pytest.skip(f"block device {test_blk_device} not empty")
+    args["devices"]["device"]["path"] = test_blk_device
+    # ensure we have a test file
+    test_input_file = tree / "test-input.txt"
+    test_input_file.write_text("test-data")
+    args["options"]["from"] = "input://tree/test-input.txt"
+
+    with contextlib.ExitStack() as cm:
+        cm.callback(
+            subprocess.check_call,
+            ["dd", "if=/dev/zero", f"of={test_blk_device}", "bs=512", "count=1"],
+        )
+
+        stage_module.main(args, args["devices"], args["options"])
+
+        assert open(test_blk_device, "rb").read(128) == b"test-data" + b'\x00' * 119