diff --git a/src/fastcs_eiger/io.py b/src/fastcs_eiger/io.py
index b4173a0..30168f8 100644
--- a/src/fastcs_eiger/io.py
+++ b/src/fastcs_eiger/io.py
@@ -79,4 +79,8 @@ async def update(self, attr: AttrR[DType_T, EigerParameterRef]) -> None:
             topic=attr,
         )
 
+        # Some values are initially `null` in api
+        if value is None:
+            value = attr.datatype.initial_value
+
         await attr.update(value)
diff --git a/tests/test_io.py b/tests/test_io.py
new file mode 100644
index 0000000..d7b4f2b
--- /dev/null
+++ b/tests/test_io.py
@@ -0,0 +1,21 @@
+import pytest
+from pytest_mock import MockerFixture
+
+from fastcs_eiger.io import EigerAttributeIO
+
+
+@pytest.mark.asyncio
+async def test_update(mocker: MockerFixture):
+    connection_mock = mocker.AsyncMock()
+    io = EigerAttributeIO(connection_mock, mocker.MagicMock(), mocker.MagicMock())
+    attr = mocker.AsyncMock()
+
+    connection_mock.get.return_value = {"value": 1}
+    await io.update(attr)
+
+    attr.update.assert_called_once_with(1)
+
+    connection_mock.get.return_value = {"value": None}
+    await io.update(attr)
+
+    attr.update.assert_called_with(attr.datatype.initial_value)