diff --git a/src/MEDWrapper/MED_Factory.cxx b/src/MEDWrapper/MED_Factory.cxx
index 5a34a963f..d9c273b65 100644
--- a/src/MEDWrapper/MED_Factory.cxx
+++ b/src/MEDWrapper/MED_Factory.cxx
@@ -46,16 +46,25 @@ extern "C"
 
 // -------------------------------------------------------------------------------------------------------------------
 // --- MED file compatibility: write using a lower major version implies append on an empty file of the target version
+//
+// *******************************************************************************************************************
+// ==> This file must be modified when MED version changes:
+// MED_MAJOR_NUM and MED_MINOR_NUM are defined in an external include from MED prerequisite: med.h
+// When MED_MAJOR_NUM or MED_MINOR_NUM changes, MED_MAJOR_EXPECTED and MED_MINOR_EXPECTED must be set accordingly
+// and MED_VERSIONS_APPEND_COMPATIBLE must be updated: The lower compatible versions may change with a new MED version
+// If the major version of MED change (for instance 4 --> 5) and if MED allows to append meshes in MED-4.x format,
+// Empty file content for MED-4.x should be provided (EMPTY_FILE_4x) and method CreateEmptyMEDFile should be updated.
+// *******************************************************************************************************************
 
 #define MED_MAJOR_EXPECTED 4
-#define MED_MINOR_EXPECTED 0
+#define MED_MINOR_EXPECTED 1
 #if MED_MAJOR_NUM != MED_MAJOR_EXPECTED
-  #error "MED major version does not correspond to the expected version, fix the minor and major compatibility values in CheckCompatibility method (MED_VERSIONS_APPEND_COMPATIBLE) and set the correct expected version"
+  #error "MED major version does not correspond to the expected version, fix the minor and major compatibility values in CheckCompatibility method (MED_VERSIONS_APPEND_COMPATIBLE) and set the correct expected version (MED_MAJOR_EXPECTED, MED_MINOR_EXPECTED)"
 #endif
-#if MED_MINOR_NUM < MED_MINOR_EXPECTED
-  #error "MED minor version does not correspond to the expected version, fix the minor and major compatibility values in CheckCompatibility method (MED_VERSIONS_APPEND_COMPATIBLE) and set the correct expected version"
+#if MED_MINOR_NUM != MED_MINOR_EXPECTED
+  #error "MED minor version does not correspond to the expected version, fix the minor and major compatibility values in CheckCompatibility method (MED_VERSIONS_APPEND_COMPATIBLE) and set the correct expected version above (MED_MAJOR_EXPECTED, MED_MINOR_EXPECTED)"
 #endif
-#define MED_VERSIONS_APPEND_COMPATIBLE {40, 32, 33} // --- 10*major + minor (the 3rd digit, release, is not used here,
+#define MED_VERSIONS_APPEND_COMPATIBLE {41, 40, 32, 33} // --- 10*major + minor (the 3rd digit, release, is not used here,
                                                     //                       med uses always the latest available)
                                                     // --- The first in the list should be the default: current version
 // --- empty med file content for the different MED versions with a different major.