diff --git a/include/lpContour.h b/include/lpContour.h
index c198414a6024e88b9084ffea66da11ba88fe47f3..81a5afaa8ef0a6667ffeccb82e717dfecb9feb2c 100644
--- a/include/lpContour.h
+++ b/include/lpContour.h
@@ -89,7 +89,7 @@ namespace lp
 
 		static void CreateNewContour(Contour& newContour,
 									 const CellIndex startCellId,
-									 const std::unordered_set<long unsigned int>& setCells,
+									 CellLists& setCells,
 									 const std::size_t bboxWidth,
 									 const std::size_t bboxHeight);
 
diff --git a/src/lpContour.cxx b/src/lpContour.cxx
index e458aabd0858214e918737ff5fba640de13a1e54..667778f19b08a80198aebc1bcefb1e0d7049695d 100644
--- a/src/lpContour.cxx
+++ b/src/lpContour.cxx
@@ -51,9 +51,10 @@ namespace lp
 		CreateNewContour(mergedContour, GridToBBox(cid1, mergedBBox, gridSizeX),  borderCells, mergedBBox.m_W, mergedBBox.m_H);
 	}
 
+
 	void ContourOperations::CreateNewContour(Contour& newContour,
 											 const CellIndex cidx,
-											 const std::unordered_set<CellIndex>& setCells,
+											 CellLists& setCells,
 											 const std::size_t bboxWidth,
 											 const std::size_t bboxHeight)
 	{