diff --git a/.gitignore b/.gitignore
index b6e4761..2ea6b6f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -127,3 +127,6 @@ dmypy.json
 
 # Pyre type checker
 .pyre/
+
+# Pycharm project settings
+.idea/
\ No newline at end of file
diff --git a/doipclient/client.py b/doipclient/client.py
index 8febfee..c3ef2a3 100644
--- a/doipclient/client.py
+++ b/doipclient/client.py
@@ -145,10 +145,10 @@ class DoIPClient:
     :param use_secure: Enables TLS. If set to True, a default SSL context is used. For more control, a preconfigured
         SSL context can be passed directly. Untested. Should be combined with changing tcp_port to 3496.
     :type use_secure: Union[bool,ssl.SSLContext]
-    :param log_level: Logging level
-    :type log_level: int
     :param auto_reconnect_tcp: Attempt to automatically reconnect TCP sockets that were closed by peer
     :type auto_reconnect_tcp: bool
+    :param vm_specific: Optional 4 byte long int
+    :type vm_specific: int, optional
 
     :raises ConnectionRefusedError: If the activation request fails
     :raises ValueError: If the IPAddress is neither an IPv4 nor an IPv6 address
@@ -166,6 +166,7 @@ def __init__(
         client_ip_address=None,
         use_secure=False,
         auto_reconnect_tcp=False,
+        vm_specific=None
     ):
         self._ecu_logical_address = ecu_logical_address
         self._client_logical_address = client_logical_address
@@ -180,6 +181,7 @@ def __init__(
         self._protocol_version = protocol_version
         self._auto_reconnect_tcp = auto_reconnect_tcp
         self._tcp_close_detected = False
+        self.vm_specific = vm_specific
 
         # Check the ECU IP type to determine socket family
         # Will raise ValueError if neither a valid IPv4, nor IPv6 address
@@ -587,16 +589,19 @@ def request_activation(
         :type disable_retry: bool, optional
         :return: The resulting activation response object
         :rtype: RoutingActivationResponse
+        :raises ValueError: vm_specific is invalid or out of range
         """
         message = RoutingActivationRequest(
-            self._client_logical_address, activation_type, vm_specific=vm_specific
+            self._client_logical_address,
+            activation_type,
+            vm_specific=self._validate_vm_specific_value(vm_specific) if vm_specific else self.vm_specific,
         )
         self.send_doip_message(message, disable_retry=disable_retry)
         while True:
             result = self.read_doip()
-            if type(result) == RoutingActivationResponse:
+            if isinstance(result, RoutingActivationResponse):
                 return result
-            elif result:
+            if result:
                 logger.warning(
                     "Received unexpected DoIP message type {}. Ignoring".format(
                         type(result)
@@ -824,3 +829,39 @@ def reconnect(self, close_delay=A_PROCESSING_TIME):
                 raise ConnectionRefusedError(
                     f"Activation Request failed with code {result.response_code}"
                 )
+
+    @staticmethod
+    def _validate_vm_specific_value(value):
+        """Validate the VM specific value (must be > 0 and <= 0xffffffff) or None.
+        If the conditions are not fulfilled, raises an exception.
+
+        :param value: The value to check.
+        :type value: int, optional
+        :return: The input value if valid.
+        :rtype: int or None
+        :raises ValueError: If the value is invalid or out of range.
+        """
+        if not isinstance(value, int) and value is not None:
+            raise ValueError("Invalid vm_specific type must be int or None")
+        if isinstance(value, int) and (value < 0 or value > 0xffffffff):
+            raise ValueError("Invalid vm_specific value must be > 0 and <= 0xffffffff")
+        return value
+
+    @property
+    def vm_specific(self):
+        """Get the optional OEM specific field value if set.
+
+        :return: vm_specific value
+        :rtype: int, optional
+        """
+        return self._vm_specific
+
+    @vm_specific.setter
+    def vm_specific(self, value):
+        """Set the optional OEM specific field value. If you do not need to send this item, set it to None.
+
+        :param value: The vm_specific value (must be > 0 and <= 0xffffffff) or None
+        :type value: int, optional
+        :raises ValueError: Value is invalid or out of range
+        """
+        self._vm_specific = self._validate_vm_specific_value(value)
diff --git a/setup.py b/setup.py
index a1b3745..01f9a4b 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
 
 setuptools.setup(
     name="doipclient",
-    version="1.1.6",
+    version="1.1.7.dev1",
     description="A Diagnostic over IP (DoIP) client implementing ISO-13400-2.",
     long_description=long_description,
     long_description_content_type="text/x-rst",
diff --git a/tests/test_client.py b/tests/test_client.py
index d85e6b6..f70c47e 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -750,3 +750,60 @@ def test_use_secure_with_external_ssl_context(mock_socket, mocker):
 
     mocked_external_wrap_socket = mocked_external_context.wrap_socket
     mocked_external_wrap_socket.assert_called_once_with(mock_socket)
+
+
+@pytest.mark.parametrize(
+    "vm_specific, exc",
+    ((None, False), (0, False), (-1, True), (0xFFFFFFFF, False), (0x100000000, True), ("0x1", True), (10.0, True)))
+def test_vm_specific_setter(mock_socket, mocker, vm_specific, exc):
+    sut = DoIPClient(test_ip, test_logical_address, auto_reconnect_tcp=True)
+    if exc:
+        with pytest.raises(ValueError):
+            sut.vm_specific = vm_specific
+    else:
+        sut.vm_specific = vm_specific
+        assert sut.vm_specific == vm_specific
+
+
+def test_vm_specific_static_value(mock_socket, mocker):
+    request_activation_spy = mocker.spy(DoIPClient, "request_activation")
+    mock_socket.rx_queue.append(successful_activation_response_with_vm)
+
+    sut = DoIPClient(
+        test_ip,
+        test_logical_address,
+        auto_reconnect_tcp=True,
+        activation_type=None,
+        vm_specific=0x01020304,
+    )
+    sut.request_activation(activation_type=RoutingActivationRequest.ActivationType.Default)
+    assert mock_socket.tx_queue[-1] == activation_request_with_vm
+    assert request_activation_spy.call_count == 1
+
+
+def test_vm_specific_request_activation_bad_value(mock_socket, mocker):
+    request_activation_spy = mocker.spy(DoIPClient, "request_activation")
+    mock_socket.rx_queue.append(successful_activation_response_with_vm)
+
+    sut = DoIPClient(
+        test_ip,
+        test_logical_address,
+        auto_reconnect_tcp=True,
+        activation_type=None,
+        vm_specific=0x01020304,
+    )
+    with pytest.raises(ValueError):
+        sut.request_activation(activation_type=RoutingActivationRequest.ActivationType.Default, vm_specific=-1)
+
+
+def test_vm_specific_verification_in_init(mock_socket, mocker):
+    request_activation_spy = mocker.spy(DoIPClient, "request_activation")
+    mock_socket.rx_queue.append(successful_activation_response_with_vm)
+    with pytest.raises(ValueError):
+        sut = DoIPClient(
+            test_ip,
+            test_logical_address,
+            auto_reconnect_tcp=True,
+            activation_type=None,
+            vm_specific=-1,
+        )
\ No newline at end of file