diff --git a/include/lsgrmGraphOperations.txx b/include/lsgrmGraphOperations.txx
index b4ef17815f08485de63fde12487feb87a188cd82..15c9b8099828ce357c57634b9d1b00081d06926b 100644
--- a/include/lsgrmGraphOperations.txx
+++ b/include/lsgrmGraphOperations.txx
@@ -97,7 +97,7 @@ MergeAllGraphsAndAchieveSegmentation(
   //  // Write output graph to the output graph directory
   //  WriteGraph<TSegmenter>(segmenter.m_Graph, tmpDir, 0, 0);
   
-  // TODO: use std::sort to sort the graph before the polygon filling
+  // TODO: use std::sort to sort the graph (m_Id must be increasing) before the polygon filling
   typename TSegmenter::LabelImageType::SizeType outSize;
   outSize[0] = imageWidth;
   outSize[1] = imageHeight;