diff --git a/CMakeLists.txt b/CMakeLists.txt
index bca2af5c7c..beaeaa1a2a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,21 +1,12 @@
+# april 2020, the oldest we have to support : Ununtu 16.04 LTS (Xenial)
 cmake_minimum_required(VERSION 3.5.1 FATAL_ERROR)
 
-if(COMMAND cmake_policy)
-    cmake_policy(SET CMP0003 NEW)
-    if(POLICY CMP0020)
-        cmake_policy(SET CMP0020 NEW)
-    endif(POLICY CMP0020)
-    # added in cmake 3.0
-    if(POLICY CMP0050)
-        cmake_policy(SET CMP0050 NEW)
-    endif(POLICY CMP0050)
-    if (POLICY CMP0045)
-        cmake_policy(SET CMP0045 NEW)
-    endif(POLICY CMP0045)
-    if (POLICY CMP0072)
-        cmake_policy(SET CMP0072 OLD)
-    endif(POLICY CMP0072)
-endif(COMMAND cmake_policy)
+# policy CMP0072 was introduced with CMake 3.11
+# relates to FindOpenGL module
+# and cache variables OPENGL_gl_LIBRARY, OPENGL_glu_LIBRARY
+if (POLICY CMP0072)
+    cmake_policy(SET CMP0072 OLD)
+endif(POLICY CMP0072)
 
 find_program(CCACHE_PROGRAM ccache)  #This check should occur before project()
 if(CCACHE_PROGRAM)