diff --git a/src/libslic3r/MutablePriorityQueue.hpp b/src/libslic3r/MutablePriorityQueue.hpp
index 68cd01859..cc1cae68c 100644
--- a/src/libslic3r/MutablePriorityQueue.hpp
+++ b/src/libslic3r/MutablePriorityQueue.hpp
@@ -354,7 +354,7 @@ inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking
 #endif /* NDEBUG */
 	{
 		// Mark as removed from the queue.
-		m_index_setter(m_heap.front(), std::numeric_limits<size_t>::max());
+		m_index_setter(m_heap[1], std::numeric_limits<size_t>::max());
 	}
 	// Zero'th element is padding, thus non-empty queue must have at least two elements.
 	if (m_heap.size() > 2) {
diff --git a/src/libslic3r/QuadricEdgeCollapse.cpp b/src/libslic3r/QuadricEdgeCollapse.cpp
index 94375ec9d..c5de1b0a7 100644
--- a/src/libslic3r/QuadricEdgeCollapse.cpp
+++ b/src/libslic3r/QuadricEdgeCollapse.cpp
@@ -151,10 +151,11 @@ void Slic3r::its_quadric_edge_collapse(
     statusfn(status_init_size);
 
     // convert from triangle index to mutable priority queue index
-    std::vector<uint32_t> ti_2_mpqi(its.indices.size(), {0});
+    std::vector<size_t> ti_2_mpqi(its.indices.size(), {0});
     auto setter = [&ti_2_mpqi](const Error &e, size_t index) { ti_2_mpqi[e.triangle_index] = index; };
     auto less = [](const Error &e1, const Error &e2) -> bool { return e1.value < e2.value; };
-    MutablePriorityQueue<Error, decltype(setter), decltype(less)> mpq(std::move(setter), std::move(less));
+    auto mpq = make_miniheap_mutable_priority_queue<Error, 32, false>(std::move(setter), std::move(less)); 
+    //MutablePriorityQueue<Error, decltype(setter), decltype(less)> mpq(std::move(setter), std::move(less));
     mpq.reserve(its.indices.size());
     for (Error &error :errors) mpq.push(error);
 
@@ -257,16 +258,14 @@ void Slic3r::its_quadric_edge_collapse(
             vi_top0, t1, ceis, e_infos_swap);
         
         // Change vertex
-        // Has to be set after subtract quadric
         its.vertices[vi0] = new_vertex0;
 
         // fix errors - must be after set neighbors - v_infos
         mpq.remove(ti_2_mpqi[ti1]);
         for (uint32_t ti : changed_triangle_indices) {
             size_t priority_queue_index = ti_2_mpqi[ti];
-            auto iterator = mpq.begin() + priority_queue_index;
             TriangleInfo& t_info = t_infos[ti];
-            *iterator = calculate_error(ti, its.indices[ti], its.vertices, v_infos, t_info.min_index);
+            mpq[priority_queue_index] = calculate_error(ti, its.indices[ti], its.vertices, v_infos, t_info.min_index);
             mpq.update(priority_queue_index);
         }