diff --git a/.github/workflows/autopep8.yml b/.github/workflows/autopep8.yml
index a866977f..999b02cb 100644
--- a/.github/workflows/autopep8.yml
+++ b/.github/workflows/autopep8.yml
@@ -20,15 +20,4 @@ jobs:
         id: check
         run: |
           # Check if autopep8 would make changes
-          formatting_issues=$(autopep8 --diff --recursive --max-line-length 120 .)
-          if [[ formatting_issues ]] then
-            echo "Formatting issues found:"
-            printf "%s\n" "$formatting_issues"
-            echo "------------------------------"
-            echo "-- Formatting issues found! --"
-            echo "------------------------------"
-            exit 1
-          else
-            echo "No formatting issues found."
-          fi
-
+          autopep8 --diff --recursive --max-line-length 120 --exit-code .
diff --git a/robotmbt/tracestate.py b/robotmbt/tracestate.py
index 9aaff77b..22526748 100644
--- a/robotmbt/tracestate.py
+++ b/robotmbt/tracestate.py
@@ -162,5 +162,9 @@ class TraceSnapShot:
     def __init__(self, id, inserted_scenario, model_state, drought=0):
         self.id = id
         self.scenario = inserted_scenario
-        self.model = model_state.copy()
+        self._model = model_state.copy()
         self.coverage_drought = drought
+
+    @property
+    def model(self):
+        return self._model.copy()