diff --git a/stock_available_to_promise_release/models/stock_move.py b/stock_available_to_promise_release/models/stock_move.py
index d59d90eb59..ac237ca06b 100644
--- a/stock_available_to_promise_release/models/stock_move.py
+++ b/stock_available_to_promise_release/models/stock_move.py
@@ -787,7 +787,9 @@ def write(self, vals):
     def _is_mergeable(self):
         self.ensure_one()
         return self.state not in ("done", "cancel") and (
-            self.picking_type_id.code != "outgoing" or self.unrelease_allowed
+            self.picking_type_id.code != "outgoing"
+            or not self._is_unreleaseable()
+            or self.unrelease_allowed
         )
 
     def _update_candidate_moves_list(self, candidate_moves):
diff --git a/stock_available_to_promise_release/tests/test_merge_moves.py b/stock_available_to_promise_release/tests/test_merge_moves.py
index 5e08bd8642..cff7ee2cc2 100644
--- a/stock_available_to_promise_release/tests/test_merge_moves.py
+++ b/stock_available_to_promise_release/tests/test_merge_moves.py
@@ -136,3 +136,15 @@ def test_unrelease_at_move_merge_merged(self):
         self.assertEqual(1, len(move))
         self.assertEqual(2 + original_qty_1 + original_qty_2, move.product_uom_qty)
         self.assertEqual(2, move.move_line_ids.qty_done)
+
+    def test_default_merge(self):
+        # check that the merge is still working when the available_to_promise_defer_pull
+        # is False
+        self.wh.delivery_route_id.write(
+            {
+                "available_to_promise_defer_pull": False,
+            }
+        )
+        # run a new procurement for the same product in the shipment 1
+        self._procure(2)
+        self.assertEqual(1, len(self.shipping1.move_ids))