diff --git a/network_process/src/post_topo/patch_propagation.cpp b/network_process/src/post_topo/patch_propagation.cpp
index d7574ad..81c71a5 100644
--- a/network_process/src/post_topo/patch_propagation.cpp
+++ b/network_process/src/post_topo/patch_propagation.cpp
@@ -141,12 +141,13 @@ dynamic_bitset_mp<> filter_cells_by_boolean(const baked_blobtree_t&
     stacked_nodes.emplace(std::move(front_info));
 
     iter++;
-    while (iter != tree.nodes.end() - 1) {
-        // each out iteration must start with leaf node
+    while (iter != tree.nodes.end()) {
+        // each out iteration must start with leaf node, only 1 leaf node is absorbed in one iteration
         assert(iter->is_primitive_node());
         compact_node_info temp_info{std::move(cell_primitive_signs[iter->primitive_index]), iter->parent_index};
         iter++; // to parent or neighboring node
-        while (temp_info.parent_index == stacked_nodes.top().parent_index) {
+        while (!stacked_nodes.empty() && temp_info.parent_index == stacked_nodes.top().parent_index) {
+            // do bool operation, util meet next primitive node.
             assert(iter->is_operation_node());
 
             const auto& other_cell_sign = stacked_nodes.top().cell_signs;
@@ -168,7 +169,7 @@ dynamic_bitset_mp<> filter_cells_by_boolean(const baked_blobtree_t&
     }
 
     assert(stacked_nodes.size() == 1);
-    assert(stacked_nodes.top().parent_index == tree.nodes.size() - 1);
+    assert(stacked_nodes.top().parent_index == 0xFFFFFFFF);
 
     return stacked_nodes.top().cell_signs;
 }
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