diff --git a/include/poly_ops/clip.hpp b/include/poly_ops/clip.hpp
index ad95cdf..390c229 100644
--- a/include/poly_ops/clip.hpp
+++ b/include/poly_ops/clip.hpp
@@ -1820,6 +1820,7 @@ template<coordinate Coord,std::integral Index=std::size_t> class clipper {
         Index s2,
         i_point_tracker<Index> *pt);
     void add_fb_events(Index sa,Index sb);
+    Index insert_anchor_point(Index i);
     void do_op(bool_op op,i_point_tracker<Index> *pt,bool TreeOut);
 
     template<point_range<Coord> R> void _add_loop(R &&loop,bool_set cat,i_point_tracker<Index> *pt) {
@@ -2271,6 +2272,19 @@ void clipper<Coord,Index>::calc_line_bal(bool_op op) {
     }
 }
 
+template<coordinate Coord,std::integral Index>
+Index clipper<Coord,Index>::insert_anchor_point(Index i) {
+    if(!(lpoints[lpoints[i].next].state() & detail::line_state::anchor)) {
+        Index new_i = Index(lpoints.size());
+        lpoints.push_back(lpoints[i]);
+        lpoints.back().state() = detail::line_state::anchor_undef;
+        lpoints[i].next = new_i;
+
+        POLY_OPS_DEBUG_LOG("Adding anchor point {} after {}",new_i,i);
+    }
+    return lpoints[i].next;
+}
+
 template<coordinate Coord,std::integral Index>
 void clipper<Coord,Index>::do_op(bool_op op,i_point_tracker<Index> *pt,bool tree_out) {
     using namespace detail;
@@ -2293,22 +2307,18 @@ void clipper<Coord,Index>::do_op(bool_op op,i_point_tracker<Index> *pt,bool tree
     overlapping line segments changing in the next few steps */
     if(tree_out) {
         for(auto &intr : samples) {
-            for(Index &i : intr.hits) {
-                if(!(lpoints[lpoints[i].next].state() & line_state::anchor)) {
-                    Index new_i = Index(lpoints.size());
-                    lpoints.push_back(lpoints[i]);
-                    lpoints.back().state() = line_state::anchor_undef;
-                    lpoints[i].next = new_i;
-
-                    POLY_OPS_DEBUG_LOG("Adding anchor point {} after {}",new_i,i);
-                }
-                i = lpoints[i].next;
-            }
+            for(Index &i : intr.hits) i = insert_anchor_point(i);
+        }
+        for(auto &intr : samples) {
+            follow_balance<Index,Coord>(
+                lpoints,
+                std::exchange(intr.p,insert_anchor_point(intr.p)),
+                breaks,pt);
+        }
+    } else {
+        for(auto &intr : samples) {
+            follow_balance<Index,Coord>(lpoints,intr.p,breaks,pt);
         }
-    }
-
-    for(auto &intr : samples) {
-        follow_balance<Index,Coord>(lpoints,intr.p,breaks,pt);
     }
 
     /* match all the orphan points to virtual points to make the virtual into
diff --git a/tests/misc_tests.cpp b/tests/misc_tests.cpp
index ec631a8..28afd57 100644
--- a/tests/misc_tests.cpp
+++ b/tests/misc_tests.cpp
@@ -34,6 +34,32 @@ void sort_by_size(auto &x) {
     std::ranges::sort(x,{},[](auto &item) { return item.items.size(); });
 }
 
+void for_each_combination(
+    std::span<std::span<const poly_ops::point_t<int>>> input,
+    auto &&fun,
+    std::vector<std::span<const poly_ops::point_t<int>>> &buffer)
+{
+    if(input.empty()) fun(buffer);
+    else {
+        std::vector<std::span<const poly_ops::point_t<int>>> current;
+        current.reserve(input.size()-1);
+        for(std::size_t i=0; i<input.size(); ++i) {
+            current.clear();
+            current.insert(current.end(),input.begin(),input.begin()+long(i));
+            current.insert(current.end(),input.begin()+(long(i)+1),input.end());
+            buffer.push_back(input[i]);
+            for_each_combination(current,fun,buffer);
+            buffer.pop_back();
+        }
+    }
+}
+void for_each_combination(std::span<std::span<const poly_ops::point_t<int>>> input,auto &&fun)
+{
+    std::vector<std::span<const poly_ops::point_t<int>>> buffer;
+    buffer.reserve(input.size());
+    for_each_combination(input,fun,buffer);
+}
+
 int main() {
     using namespace boost::ut;
 
@@ -63,10 +89,13 @@ int main() {
             {230,255}
         }};
 
-        /* This shape should decompose into exactly 10 shapes and 0 holes */
-        auto out = poly_ops::normalize_op<true,int>(loops);
-        expect(out.size() == 10_u);
-        expect(std::ranges::all_of(out,[](auto loop) { return loop.inner_loops().size() == 0; }));
+        std::vector<std::span<const poly_ops::point_t<int>>> current{loops.begin(),loops.end()};
+        for_each_combination(current,[](auto &data) {
+            /* This shape should decompose into exactly 10 shapes and 0 holes */
+            auto out = poly_ops::normalize_op<true,int>(data);
+            expect(out.size() == 10_u);
+            expect(std::ranges::all_of(out,[](auto loop) { return loop.inner_loops().size() == 0; }));
+        });
     };
 
     "Test nesting"_test = [] {