diff --git a/src/voloctree/voloctree.cpp b/src/voloctree/voloctree.cpp
index 49c30c47a4..48eb47ceb4 100644
--- a/src/voloctree/voloctree.cpp
+++ b/src/voloctree/voloctree.cpp
@@ -1599,6 +1599,7 @@ VolOctree::StitchInfo VolOctree::deleteCells(const std::vector<DeleteInfo> &dele
 			m_cellToOctant.erase(cellId);
 
 			auto octantToCellItr = m_octantToCell.find(treeId);
+			assert(octantToCellItr != m_octantToCell.end());
 			if (octantToCellItr->second == cellId) {
 				m_octantToCell.erase(octantToCellItr);
 			}
@@ -1606,6 +1607,7 @@ VolOctree::StitchInfo VolOctree::deleteCells(const std::vector<DeleteInfo> &dele
 			m_cellToGhost.erase(cellId);
 
 			auto ghostToCellItr = m_ghostToCell.find(treeId);
+			assert(ghostToCellItr != m_ghostToCell.end());
 			if (ghostToCellItr->second == cellId) {
 				m_ghostToCell.erase(ghostToCellItr);
 			}