diff --git a/src/coord.h b/src/coord.h
index 1ae4fca..63b0b2f 100644
--- a/src/coord.h
+++ b/src/coord.h
@@ -33,6 +33,8 @@ struct Coord
             default    : x= 0; y= 0; break;
         }
     }
+    bool operator==(const Coord &c) const
+        { return x==c.x&&y==c.y;}
     Coord operator+(const Coord &c) const
         { return Coord(x+c.x, y+c.y);}
     Coord& operator+=(const Coord &c)
@@ -69,6 +71,13 @@ struct Coord
         { return dist(*this, c); }
     int dist(int x, int y) const
         { return dist(*this, Coord(x, y)); }
+
+};
+
+struct CoordHash{
+    size_t operator()(const Coord& val) const{
+        return val.x+10000*val.y;
+    }
 };
 
 #endif // COORD_H
diff --git a/src/mapscene.cpp b/src/mapscene.cpp
index 2cccbc1..6c727e2 100644
--- a/src/mapscene.cpp
+++ b/src/mapscene.cpp
@@ -104,5 +104,6 @@ void MapScene::draw()
 
     // clearing temporary data structures
     m_updatedCoordMap.clear();
+    m_updatedCoordMap.rehash(0);
     m_pixels.clear();
 }
diff --git a/src/mapscene.h b/src/mapscene.h
index 457f882..e006eec 100644
--- a/src/mapscene.h
+++ b/src/mapscene.h
@@ -6,7 +6,7 @@
 #include <glm/vec2.hpp>
 #include <glm/vec3.hpp>
 #include <QMutex>
-#include <map>
+#include <unordered_map>
 
 struct MapScene : public Map, public BasicScene
 {
@@ -48,7 +48,7 @@ private:
         Pix(glm::vec2 p, glm::vec3 c) : pos(p), color(c) {}
     };
     std::vector<Pix> m_pixels;
-    std::map<Coord, int> m_updatedCoordMap;
+    std::unordered_map<Coord, int, CoordHash> m_updatedCoordMap;
 };
 
 #endif // MAPSCENE_H