diff --git a/plin/device.py b/plin/device.py
index 2301eda..392ed89 100644
--- a/plin/device.py
+++ b/plin/device.py
@@ -99,10 +99,11 @@ def set_frame_entry(self,
         IMPORTANT NOTE: For a publisher frame, the flag PLINFrameFlag.RSP_ENABLE must be set in order to allow a slave response.
         This flag is set by default if the frame direction is publisher for convenience.
         '''
-        buffer = PLINUSBFrameEntry(
-            id=id, direction=direction, checksum=checksum_type)
         if direction == PLINFrameDirection.PUBLISHER:
-            buffer.flags = flags & PLINFrameFlag.RSP_ENABLE
+            flags |= PLINFrameFlag.RSP_ENABLE
+
+        buffer = PLINUSBFrameEntry(
+            id=id, direction=direction, checksum=checksum_type, flags=flags)
         if data:
             buffer.d = data
         if len > 0:
diff --git a/tests/unit/__init__.py b/tests/unit/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/unit/test_plin_device.py b/tests/unit/test_plin_device.py
new file mode 100644
index 0000000..6b27ed2
--- /dev/null
+++ b/tests/unit/test_plin_device.py
@@ -0,0 +1,98 @@
+import sys
+from unittest.mock import patch, MagicMock
+
+import pytest
+
+from plin.enums import (
+    PLINMode,
+    PLINFrameDirection,
+    PLINFrameChecksumType,
+    PLINFrameFlag,
+)
+
+FCNTL_MOD_NAME = "fcntl"
+
+
+class TestUnitPLIN:
+    @pytest.fixture(scope="class")
+    def mock_fcntl_mod(self):
+        """Mock the fcntl module
+
+        The module does not exist on Windows, but the unit test should be runnable
+        on any system.
+        """
+        has_module = FCNTL_MOD_NAME in sys.modules
+        orig = sys.modules.get(FCNTL_MOD_NAME)
+
+        fcntl_mock = sys.modules[FCNTL_MOD_NAME] = MagicMock()
+        yield fcntl_mock
+
+        if has_module:
+            sys.modules[FCNTL_MOD_NAME] = orig
+        else:
+            del sys.modules[FCNTL_MOD_NAME]
+
+    @pytest.fixture
+    def plin_master_unit(self, mock_fcntl_mod: MagicMock):
+        """Create a PLIN master object with mocked fopen and ioctl"""
+
+        # We must import here after fcntl has been mocked
+        # because the module does not exist on Windows
+        from plin.device import PLIN
+
+        plin = PLIN("/dev/plin0")
+        with patch("os.open") as mock_open:
+            mock_ioctl = mock_fcntl_mod.ioctl
+            plin.start(PLINMode.MASTER)
+
+            mock_open.reset_mock()
+            mock_ioctl.reset_mock()
+
+            yield plin, mock_open, mock_ioctl
+
+    @pytest.mark.parametrize("data", (None, bytearray(b"1234")))
+    @pytest.mark.parametrize(
+        "flags, direction",
+        [
+            (PLINFrameFlag.NONE, PLINFrameDirection.PUBLISHER),
+            (PLINFrameFlag.SINGLE_SHOT, PLINFrameDirection.PUBLISHER),
+            (PLINFrameFlag.NONE, PLINFrameDirection.SUBSCRIBER),
+        ],
+    )
+    def test_set_frame_entry(
+        self,
+        plin_master_unit,
+        data: bytearray,
+        flags: PLINFrameFlag,
+        direction: PLINFrameDirection,
+    ):
+        plin, mock_open, mock_ioctl = plin_master_unit
+
+        plin.set_frame_entry(
+            0x22,
+            direction=direction,
+            checksum_type=PLINFrameChecksumType.CLASSIC,
+            flags=flags,
+            data=data,
+            len=len(data) if data else 0,
+        )
+
+        assert len(mock_ioctl.mock_calls) == 1
+        fd, ioctl_num, arg = mock_ioctl.mock_calls[0].args
+
+        assert ioctl_num == 1074820354
+        assert arg.id == 0x22
+        assert arg.direction == direction
+        assert arg.checksum == PLINFrameChecksumType.CLASSIC
+        assert arg.len == (len(data) if data else 0)
+
+        # We just compare the first data byte
+        if data is not None:
+            assert arg.d[0] == data[0]
+        else:
+            assert arg.d[0] == 0
+
+        if direction == PLINFrameDirection.PUBLISHER:
+            assert arg.flags == PLINFrameFlag.RSP_ENABLE | flags
+        else:
+            assert arg.flags == flags