diff --git a/src/ophyd_async/core/_readable.py b/src/ophyd_async/core/_readable.py
index 261ce6cc9e..d0fa3086ba 100644
--- a/src/ophyd_async/core/_readable.py
+++ b/src/ophyd_async/core/_readable.py
@@ -1,7 +1,6 @@
 import asyncio
 import warnings
 from contextlib import contextmanager
-from dataclasses import dataclass
 from typing import (
     Any,
     Callable,
@@ -31,13 +30,12 @@
 T = TypeVar("T")
 
 
-@dataclass
 class PerSignalConfig(Dict[SignalW, Any]):
     def __setitem__(self, signal: SignalW[T], value: T):
         super().__setitem__(signal, value)
 
     def __getitem__(self, signal: SignalW[T]) -> T:
-        return super().__getitem__[signal]
+        return super().__getitem__(signal)
 
 
 class StandardReadable(
diff --git a/tests/core/test_readable.py b/tests/core/test_readable.py
index 9126dc7587..e917f4efb4 100644
--- a/tests/core/test_readable.py
+++ b/tests/core/test_readable.py
@@ -268,10 +268,6 @@ def standard_readable_config():
 ]
 
 
-def test_config_initialization(standard_readable_config):
-    assert len(standard_readable_config) == 0
-
-
 @pytest.mark.parametrize("name, type_, value", test_data)
 def test_config_set_get_item(standard_readable_config, name, type_, value):
     mock_signal = MagicMock(spec=SignalW)