diff --git a/src/dihedral_angles_filter.cc b/src/dihedral_angles_filter.cc
index 9040ad7..88c28d6 100644
--- a/src/dihedral_angles_filter.cc
+++ b/src/dihedral_angles_filter.cc
@@ -72,6 +72,7 @@ vtkTypeBool DihedralAnglesFilter::RequestData(
 
 		i += 6;
 	}
+	it->Delete();
 	AverageMinDegrees /= input->GetNumberOfCells();
 	AverageMinDegrees = AverageMinDegrees * 180. / 3.141592653589793;
 	MinMinDegrees = MinMinDegrees * 180. / 3.141592653589793;
diff --git a/src/main.cc b/src/main.cc
index efbebcc..baaaa5e 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -37,7 +37,7 @@
 #include <array>
 
 
-vtkSmartPointer<vtkAlgorithm> readerFromFileName(const char *fileName) {
+vtkAlgorithm *readerFromFileName(const char *fileName) {
 	std::string extension =
 		vtksys::SystemTools::GetFilenameLastExtension(fileName);
 	if (extension == ".vtk") {
@@ -148,5 +148,7 @@ int main(int argc, char **argv) {
 	renderWindow->Render();
 	renderWindowInteractor->Start();
 #endif
+	tetMeshReader->Delete();
+	polyMeshReader->Delete();
 	return EXIT_SUCCESS;
 }
diff --git a/src/remove_external_cells_filter.cc b/src/remove_external_cells_filter.cc
index 55dafa2..6fb5c53 100644
--- a/src/remove_external_cells_filter.cc
+++ b/src/remove_external_cells_filter.cc
@@ -60,6 +60,7 @@ vtkTypeBool RemoveExternalCellsFilter::RequestData(
 			outCells->InsertNextCell(it->GetPointIds());
 		}
 	}
+	it->Delete();
 	output->SetCells(VTK_TETRA, outCells);
 	output->SetPoints(tetMesh->GetPoints());
 
diff --git a/src/surface_points_filter.cc b/src/surface_points_filter.cc
index 6b73428..d950367 100644
--- a/src/surface_points_filter.cc
+++ b/src/surface_points_filter.cc
@@ -72,6 +72,7 @@ vtkTypeBool SurfacePointsFilter::RequestData(
 			}
 		}
 	}
+	it->Delete();
 	surfacePoints->Allocate(surfacePointsSet.size());
 	for (const vtkIdType &id : surfacePointsSet) {
 		surfacePoints->InsertNextValue(id);