diff --git a/ophyd_devices/sim/sim_frameworks/h5_image_replay_proxy.py b/ophyd_devices/sim/sim_frameworks/h5_image_replay_proxy.py
index 2570838..7703849 100644
--- a/ophyd_devices/sim/sim_frameworks/h5_image_replay_proxy.py
+++ b/ophyd_devices/sim/sim_frameworks/h5_image_replay_proxy.py
@@ -39,6 +39,7 @@ class H5ImageReplayProxy(DeviceProxy):
 
     @file_source.setter
     def file_source(self, file_source: str) -> None:
+        self.config[list(self.config.keys())[0]]["file_source"] = file_source
         self._file_source = file_source
 
     @property
@@ -48,6 +49,7 @@ class H5ImageReplayProxy(DeviceProxy):
 
     @h5_entry.setter
     def h5_entry(self, h5_entry: str) -> None:
+        self.config[list(self.config.keys())[0]]["h5_entry"] = h5_entry
         self._h5_entry = h5_entry
 
     def _update_device_config(self, config: dict) -> None:
diff --git a/tests/test_simulation.py b/tests/test_simulation.py
index 95b0324..c18d4c3 100644
--- a/tests/test_simulation.py
+++ b/tests/test_simulation.py
@@ -453,6 +453,23 @@ def test_slitproxy(slitproxy_fixture):
     assert (img[:, edges[1] :] == 0).all()
 
 
+def test_proxy_config_and_props_stay_in_sync(h5proxy_fixture: tuple[H5ImageReplayProxy, SimCamera]):
+    h5proxy, cam = h5proxy_fixture
+    h5proxy._update_device_config(
+        {
+            cam.name: {
+                "signal_name": "image",
+                "file_source": "test first thing",
+                "h5_entry": "/entry/data/data",
+            }
+        }
+    )
+    h5proxy.file_source = "test different thing"
+    assert h5proxy.config[cam.name]["file_source"] == h5proxy.file_source
+    h5proxy.h5_entry = "/entry/data/data_000001"
+    assert h5proxy.config[cam.name]["h5_entry"] == h5proxy.h5_entry
+
+
 def test_cam_stage_h5writer(camera):
     """Test the H5Writer class"""
     with (