diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0e5e13434..969ad1a28 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -49,6 +49,9 @@ jobs:
           python3 -m pip install black==22.6.0
           python3 -m black --check --exclude=unified_planning/grpc/generated/ .
 
+      - name: MyPy version
+        run: python3 -m mypy --version
+
       - name: MyPy check
         run: python3 -m mypy unified_planning
 
diff --git a/unified_planning/model/delta_stn.py b/unified_planning/model/delta_stn.py
index a67ec5c45..2cf54ce16 100644
--- a/unified_planning/model/delta_stn.py
+++ b/unified_planning/model/delta_stn.py
@@ -148,18 +148,18 @@ def _is_subsumed(self, x: Any, y: Any, b: T) -> bool:
     def _inc_check(self, x: Any, y: Any, b: T) -> bool:
         x_dist = self._distances[x]
         x_plus_b = x_dist + b
-        if x_plus_b < self._distances[y]:
-            self._distances[y] = x_plus_b
+        if x_plus_b < self._distances[y]:  # type: ignore[operator]
+            self._distances[y] = x_plus_b  # type: ignore[assignment]
             queue: Deque[Any] = deque()
             queue.append(y)
             while queue:
                 c = queue.popleft()
                 n = self._constraints[c]
                 while n is not None:
-                    if self._distances[c] + n.bound < self._distances[n.dst]:
-                        if n.dst == y and abs(n.bound - b) <= self._epsilon:
+                    if self._distances[c] + n.bound < self._distances[n.dst]:  # type: ignore[operator]
+                        if n.dst == y and abs(n.bound - b) <= self._epsilon:  # type: ignore[arg-type, operator]
                             return False
-                        self._distances[n.dst] = self._distances[c] + n.bound
+                        self._distances[n.dst] = self._distances[c] + n.bound  # type: ignore[assignment]
                         queue.append(n.dst)
                     n = n.next
         return True
@@ -191,7 +191,7 @@ def insert_interval(
             to the right_event. If None the maximum length is set to +infinity.
         """
         if left_bound is not None:
-            self.add(left_event, right_event, -left_bound)
+            self.add(left_event, right_event, -left_bound)  # type: ignore[arg-type]
         if right_bound is not None:
             self.add(right_event, left_event, right_bound)
         if left_bound is None and right_bound is None: