diff --git a/generator/tesselator.cpp b/generator/tesselator.cpp
index 89b4fd6188..3b180f9285 100644
--- a/generator/tesselator.cpp
+++ b/generator/tesselator.cpp
@@ -49,7 +49,10 @@ int TesselateInterior(PolygonsT const & polys, TrianglesInfo & info)
     TESSindex const * elements = tessGetElements(tess.get());
     info.Reserve(elementCount);
     for (int i = 0; i < elementCount; ++i)
-      info.Add(elements[i * 3], elements[i * 3 + 1], elements[i * 3 + 2]);
+    {
+      if (!info.Add(elements[i * 3], elements[i * 3 + 1], elements[i * 3 + 2]))
+        return 0;
+    }
   }
   return elementCount;
 }
@@ -60,23 +63,22 @@ int TesselateInterior(PolygonsT const & polys, TrianglesInfo & info)
 
   int TrianglesInfo::ListInfo::empty_key = -1;
 
-  void TrianglesInfo::ListInfo::AddNeighbour(int p1, int p2, int trg)
+  bool TrianglesInfo::ListInfo::AddNeighbour(int p1, int p2, int trg)
   {
-    // find or insert element for key
-    std::pair<TNeighbours::iterator, bool> ret = m_neighbors.insert(std::make_pair(std::make_pair(p1, p2), trg));
-
-    // triangles should not duplicate
-    CHECK ( ret.second, ("Duplicating triangles for indices : ", p1, p2) );
+    return m_neighbors.insert({{p1, p2}, trg}).second;
   }
 
-  void TrianglesInfo::ListInfo::Add(int p0, int p1, int p2)
+  bool TrianglesInfo::ListInfo::Add(int p0, int p1, int p2)
   {
-    m_triangles.emplace_back(p0, p1, p2);
+    int const trg = static_cast<int>(m_triangles.size());
+    if (!AddNeighbour(p0, p1, trg) || !AddNeighbour(p1, p2, trg) || !AddNeighbour(p2, p0, trg))
+    {
+      LOG(LERROR, ("Duplicating triangle {", p0, p1, p2, "}"));
+      return false;
+    }
 
-    int const trg = static_cast<int>(m_triangles.size()) - 1;
-    AddNeighbour(p0, p1, trg);
-    AddNeighbour(p1, p2, trg);
-    AddNeighbour(p2, p0, trg);
+    m_triangles.emplace_back(p0, p1, p2);
+    return true;
   }
 
   template <class IterT> size_t GetBufferSize(IterT b, IterT e)
@@ -236,9 +238,9 @@ int TesselateInterior(PolygonsT const & polys, TrianglesInfo & info)
     //  MakeTrianglesChainImpl<edge_less_delta>(points, start, chain);
   }
 
-  void TrianglesInfo::Add(int p0, int p1, int p2)
+  bool TrianglesInfo::Add(int p0, int p1, int p2)
   {
-    m_triangles.back().Add(p0, p1, p2);
+    return m_triangles.back().Add(p0, p1, p2);
   }
 
   void TrianglesInfo::GetPointsInfo(m2::PointU const & baseP,
diff --git a/generator/tesselator.hpp b/generator/tesselator.hpp
index e6e2233ca8..2109770f0e 100644
--- a/generator/tesselator.hpp
+++ b/generator/tesselator.hpp
@@ -76,7 +76,7 @@ namespace tesselator
       using TNeighbours = std::unordered_map<std::pair<int, int>, int, HashPair<int, int>>;
       TNeighbours m_neighbors;
 
-      void AddNeighbour(int p1, int p2, int trg);
+      bool AddNeighbour(int p1, int p2, int trg);
 
       void GetNeighbors(
           Triangle const & trg, Triangle const & from, int * nb) const;
@@ -87,12 +87,12 @@ namespace tesselator
     public:
       using TIterator = TNeighbours::const_iterator;
 
-      ListInfo(size_t count)
+      explicit ListInfo(size_t count)
       {
         m_triangles.reserve(count);
       }
 
-      void Add(int p0, int p1, int p2);
+      bool Add(int p0, int p1, int p2);
 
       void Start() const
       {
@@ -134,14 +134,14 @@ namespace tesselator
 
     void Reserve(size_t count) { m_triangles.push_back(ListInfo(count)); }
 
-    void Add(int p0, int p1, int p2);
+    bool Add(int p0, int p1, int p2);
     //@}
 
     inline bool IsEmpty() const { return m_triangles.empty(); }
 
-    template <class ToDo> void ForEachTriangle(ToDo toDo) const
+    template <class ToDo> void ForEachTriangle(ToDo && toDo) const
     {
-      for (std::list<ListInfo>::const_iterator i = m_triangles.begin(); i != m_triangles.end(); ++i)
+      for (auto i = m_triangles.begin(); i != m_triangles.end(); ++i)
       {
         size_t const count = i->GetCount();
         for (size_t j = 0; j < count; ++j)