diff -up iso2mesh-1.9.6/tools/cgalmesh/CMakeLists.txt~ iso2mesh-1.9.6/tools/cgalmesh/CMakeLists.txt
--- iso2mesh-1.9.6/tools/cgalmesh/CMakeLists.txt~	2020-09-05 21:56:08.000000000 +0200
+++ iso2mesh-1.9.6/tools/cgalmesh/CMakeLists.txt	2021-07-20 11:17:50.726256258 +0200
@@ -4,12 +4,7 @@
 
 project( Mesh_3_example )
 
-cmake_minimum_required(VERSION 2.6.2)
-if("${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}" VERSION_GREATER 2.8.3)
-  cmake_policy(VERSION 2.8.4)
-else()
-  cmake_policy(VERSION 2.6)
-endif()
+cmake_minimum_required(VERSION 3.1...3.21)
 
 include_directories(../../include)
 include_directories(../../../Triangulation_3/include)
@@ -32,7 +27,7 @@ if ( CGAL_FOUND )
   option(ACTIVATE_CONCURRENT_MESH_3
     "Activate parallelism in Mesh_3"
     OFF)
-    
+
   # And add -DCGAL_CONCURRENT_MESH_3 if that option is ON
   if( ACTIVATE_CONCURRENT_MESH_3 OR ENV{ACTIVATE_CONCURRENT_MESH_3} )
     add_definitions( -DCGAL_CONCURRENT_MESH_3 )
@@ -45,7 +40,7 @@ if ( CGAL_FOUND )
       find_package( TBB )
     endif( LINK_WITH_TBB )
   endif()
-  
+
   if( TBB_FOUND )
     include(${TBB_USE_FILE})
     list(APPEND CGAL_3RD_PARTY_LIBRARIES ${TBB_LIBRARIES})
@@ -74,4 +69,3 @@ if ( CGAL_FOUND )
 else()
   message(STATUS "This program requires the CGAL library, and will not be compiled.")
 endif()
-
diff -up iso2mesh-1.9.6/tools/cgalsimp2/CMakeLists.txt~ iso2mesh-1.9.6/tools/cgalsimp2/CMakeLists.txt
--- iso2mesh-1.9.6/tools/cgalsimp2/CMakeLists.txt~	2020-09-05 21:56:08.000000000 +0200
+++ iso2mesh-1.9.6/tools/cgalsimp2/CMakeLists.txt	2021-07-20 11:18:34.737708589 +0200
@@ -4,22 +4,9 @@
 project( Surface_mesh_simplification )
 
 
-cmake_minimum_required(VERSION 2.6.2)
-if("${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}" VERSION_GREATER 2.6)
-  if("${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}" VERSION_GREATER 2.8.3)
-    cmake_policy(VERSION 2.8.4)
-  else()
-    cmake_policy(VERSION 2.6)
-  endif()
-endif()
+cmake_minimum_required(VERSION 3.1...3.21)
 
 set( CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true )
- 
-if ( COMMAND cmake_policy )
-
-  cmake_policy( SET CMP0003 NEW )  
-
-endif()
 
 # CGAL and its components
 find_package( CGAL QUIET COMPONENTS  )
@@ -27,7 +14,7 @@ find_package( CGAL QUIET COMPONENTS  )
 if ( NOT CGAL_FOUND )
 
   message(STATUS "This project requires the CGAL library, and will not be compiled.")
-  return()  
+  return()
 
 endif()
 
@@ -42,7 +29,7 @@ if ( NOT Boost_FOUND )
 
   message(STATUS "This project requires the Boost library, and will not be compiled.")
 
-  return()  
+  return()
 
 endif()
 
diff -up iso2mesh-1.9.6/tools/cgalsurf/CMakeLists.txt~ iso2mesh-1.9.6/tools/cgalsurf/CMakeLists.txt
--- iso2mesh-1.9.6/tools/cgalsurf/CMakeLists.txt~	2020-09-05 21:56:08.000000000 +0200
+++ iso2mesh-1.9.6/tools/cgalsurf/CMakeLists.txt	2021-07-20 11:18:16.986526147 +0200
@@ -3,12 +3,7 @@
 
 project( Surface_mesher_example )
 
-cmake_minimum_required(VERSION 2.6.2)
-if("${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}" VERSION_GREATER 2.8.3)
-  cmake_policy(VERSION 2.8.4)
-else()
-  cmake_policy(VERSION 2.6)
-endif()
+cmake_minimum_required(VERSION 3.1...3.21)
 
 include_directories(../../include)
 
@@ -26,8 +21,7 @@ else()
   if(RUNNING_CGAL_AUTO_TEST)
     # Just to avoid a warning from CMake if that variable is set on the command line...
   endif()
-  
+
   message(STATUS "NOTICE: This program requires the CGAL and CGAL ImageIO libraries, and will not be compiled.")
-  
-endif()
 
+endif()