diff --git a/plugins/state_monitor.py b/plugins/state_monitor.py
index 6f98175..a4e3871 100644
--- a/plugins/state_monitor.py
+++ b/plugins/state_monitor.py
@@ -152,11 +152,12 @@ def now_then(key):
                     "%s data: %r", pretty_name,
                     {key: str(value) for key, value in data.items()})
 
-        # Update state for next pass through the pipeline
-        self._previous_data = input_data
+        finally:
+            # Update state for next pass through the pipeline
+            self._previous_data = input_data
 
-        # Pass through the input for consumption by any further steps
-        return input_data
+            # Pass through the input for consumption by any further steps
+            return input_data
 
     def send_message(self, msg):
         """