diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3e03e9e..9b35441 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -44,28 +44,28 @@ target_compile_features(pfe PRIVATE cxx_std_17)
 
 target_sources(pfe PRIVATE
   src/main.cc
-  src/angles_filter.cc
-  src/angles_filter.h
-  src/aspect_ratio_filter.cc
-  src/aspect_ratio_filter.h
-  src/dihedral_angles_filter.cc
-  src/dihedral_angles_filter.h
+  src/analysis/angles_filter.cc
+  src/analysis/angles_filter.h
+  src/analysis/aspect_ratio_filter.cc
+  src/analysis/aspect_ratio_filter.h
+  src/analysis/dihedral_angles_filter.cc
+  src/analysis/dihedral_angles_filter.h
   src/surface_points_filter.cc
   src/surface_points_filter.h
   src/kd_tree.cc
   src/kd_tree.h
-  src/mesh_fit_filter.cc
-  src/mesh_fit_filter.h
+  src/fitting/mesh_fit_filter.cc
+  src/fitting/mesh_fit_filter.h
   src/point_tris_dist.cc
   src/point_tris_dist.h
-  src/project_surface_points_on_poly.cc
-  src/project_surface_points_on_poly.h
-  src/remove_external_cells_filter.cc
-  src/remove_external_cells_filter.h
-  src/relaxation_filter.cc
-  src/relaxation_filter.h
-  src/max_distance_filter.cc
-  src/max_distance_filter.h
+  src/fitting/project_surface_points_on_poly.cc
+  src/fitting/project_surface_points_on_poly.h
+  src/fitting/remove_external_cells_filter.cc
+  src/fitting/remove_external_cells_filter.h
+  src/fitting/relaxation_filter.cc
+  src/fitting/relaxation_filter.h
+  src/analysis/max_distance_filter.cc
+  src/analysis/max_distance_filter.h
   src/closest_polymesh_point.cc
   src/closest_polymesh_point.h)
 
diff --git a/src/angles_filter.cc b/src/analysis/angles_filter.cc
similarity index 100%
rename from src/angles_filter.cc
rename to src/analysis/angles_filter.cc
diff --git a/src/angles_filter.h b/src/analysis/angles_filter.h
similarity index 100%
rename from src/angles_filter.h
rename to src/analysis/angles_filter.h
diff --git a/src/aspect_ratio_filter.cc b/src/analysis/aspect_ratio_filter.cc
similarity index 100%
rename from src/aspect_ratio_filter.cc
rename to src/analysis/aspect_ratio_filter.cc
diff --git a/src/aspect_ratio_filter.h b/src/analysis/aspect_ratio_filter.h
similarity index 100%
rename from src/aspect_ratio_filter.h
rename to src/analysis/aspect_ratio_filter.h
diff --git a/src/dihedral_angles_filter.cc b/src/analysis/dihedral_angles_filter.cc
similarity index 100%
rename from src/dihedral_angles_filter.cc
rename to src/analysis/dihedral_angles_filter.cc
diff --git a/src/dihedral_angles_filter.h b/src/analysis/dihedral_angles_filter.h
similarity index 100%
rename from src/dihedral_angles_filter.h
rename to src/analysis/dihedral_angles_filter.h
diff --git a/src/max_distance_filter.cc b/src/analysis/max_distance_filter.cc
similarity index 98%
rename from src/max_distance_filter.cc
rename to src/analysis/max_distance_filter.cc
index c97f405..d970586 100644
--- a/src/max_distance_filter.cc
+++ b/src/analysis/max_distance_filter.cc
@@ -1,5 +1,5 @@
 #include "max_distance_filter.h"
-#include "closest_polymesh_point.h"
+#include "../closest_polymesh_point.h"
 
 #include <limits>
 #include <vtkPolyData.h>
diff --git a/src/max_distance_filter.h b/src/analysis/max_distance_filter.h
similarity index 100%
rename from src/max_distance_filter.h
rename to src/analysis/max_distance_filter.h
diff --git a/src/mesh_fit_filter.cc b/src/fitting/mesh_fit_filter.cc
similarity index 98%
rename from src/mesh_fit_filter.cc
rename to src/fitting/mesh_fit_filter.cc
index 9225a37..f8545ac 100644
--- a/src/mesh_fit_filter.cc
+++ b/src/fitting/mesh_fit_filter.cc
@@ -6,7 +6,7 @@
 #include <vtkDoubleArray.h>
 #include <vtkCellIterator.h>
 
-#include "kd_tree.h"
+#include "../kd_tree.h"
 
 vtkStandardNewMacro(MeshFitFilter);
 
diff --git a/src/mesh_fit_filter.h b/src/fitting/mesh_fit_filter.h
similarity index 100%
rename from src/mesh_fit_filter.h
rename to src/fitting/mesh_fit_filter.h
diff --git a/src/project_surface_points_on_poly.cc b/src/fitting/project_surface_points_on_poly.cc
similarity index 99%
rename from src/project_surface_points_on_poly.cc
rename to src/fitting/project_surface_points_on_poly.cc
index be8b1a2..7387e7a 100644
--- a/src/project_surface_points_on_poly.cc
+++ b/src/fitting/project_surface_points_on_poly.cc
@@ -1,5 +1,5 @@
 #include "project_surface_points_on_poly.h"
-#include "closest_polymesh_point.h"
+#include "../closest_polymesh_point.h"
 
 #include <vtkUnstructuredGrid.h>
 #include <vtkPointData.h>
diff --git a/src/project_surface_points_on_poly.h b/src/fitting/project_surface_points_on_poly.h
similarity index 100%
rename from src/project_surface_points_on_poly.h
rename to src/fitting/project_surface_points_on_poly.h
diff --git a/src/relaxation_filter.cc b/src/fitting/relaxation_filter.cc
similarity index 100%
rename from src/relaxation_filter.cc
rename to src/fitting/relaxation_filter.cc
diff --git a/src/relaxation_filter.h b/src/fitting/relaxation_filter.h
similarity index 100%
rename from src/relaxation_filter.h
rename to src/fitting/relaxation_filter.h
diff --git a/src/remove_external_cells_filter.cc b/src/fitting/remove_external_cells_filter.cc
similarity index 98%
rename from src/remove_external_cells_filter.cc
rename to src/fitting/remove_external_cells_filter.cc
index 6fb5c53..9695c4f 100644
--- a/src/remove_external_cells_filter.cc
+++ b/src/fitting/remove_external_cells_filter.cc
@@ -1,5 +1,5 @@
 #include "remove_external_cells_filter.h"
-#include "point_tris_dist.h"
+#include "../point_tris_dist.h"
 
 #include <vtkCellType.h>
 #include <vtkUnstructuredGrid.h>
diff --git a/src/remove_external_cells_filter.h b/src/fitting/remove_external_cells_filter.h
similarity index 100%
rename from src/remove_external_cells_filter.h
rename to src/fitting/remove_external_cells_filter.h
diff --git a/src/main.cc b/src/main.cc
index a8c3e52..854de21 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -1,9 +1,9 @@
-#include "dihedral_angles_filter.h"
-#include "remove_external_cells_filter.h"
+#include "analysis/dihedral_angles_filter.h"
+#include "analysis/max_distance_filter.h"
+#include "fitting/remove_external_cells_filter.h"
+#include "fitting/project_surface_points_on_poly.h"
+#include "fitting/relaxation_filter.h"
 #include "surface_points_filter.h"
-#include "project_surface_points_on_poly.h"
-#include "relaxation_filter.h"
-#include "max_distance_filter.h"
 
 #include <vtkGeometryFilter.h>
 #include <vtkCellArrayIterator.h>