diff --git a/include/tool/tool_event.h b/include/tool/tool_event.h
index 68427e14d1..c75603d1dd 100644
--- a/include/tool/tool_event.h
+++ b/include/tool/tool_event.h
@@ -444,7 +444,7 @@ public:
     template<typename T>
     void SetParameter(T aParam)
     {
-        m_param = (void*) aParam;
+        m_param = reinterpret_cast<void*>( aParam );
     }
 
     OPT<int> GetCommandId() const
diff --git a/include/undo_redo_container.h b/include/undo_redo_container.h
index 3b292f68a6..13d39756c1 100644
--- a/include/undo_redo_container.h
+++ b/include/undo_redo_container.h
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2009 jean-pierre.charras@gipsa-lab.inpg.fr
  * Copyright (C) 2011 Wayne Stambaugh <stambaughw@gmail.com>
- * Copyright (C) 2009-2020 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2009-2021 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -54,22 +54,23 @@ class BASE_SCREEN;
  * Each type must be redo/undone by a specific operation.
  */
 enum class UNDO_REDO {
-    UNSPECIFIED = 0,     // illegal
-    NOP,                 // Undo/redo will ignore this entry.  Only forces the start of a new stack
-    CHANGED,             // params of items have a value changed: undo is made by exchange
-                         // values with a copy of these values
-    NEWITEM,             // new item, undo by changing in deleted
-    DELETED,             // deleted item, undo by changing in deleted
-    LIBEDIT,             // Specific to the component editor (symbol_editor creates a full copy
-                         // of the current component when changed)
-    LIB_RENAME,          // As LIBEDIT, but old copy should be removed from library
-    EXCHANGE_T,          // Use for changing the schematic text type where swapping
-                         // data structure is insufficient to restore the change.
-    DRILLORIGIN,         // origin changed (like CHANGED, contains the origin and a copy)
-    GRIDORIGIN,          // origin changed (like CHANGED, contains the origin and a copy)
-    PAGESETTINGS,        // page settings or title block changes
-    GROUP,
-    UNGROUP
+    UNSPECIFIED = 0,    // illegal
+    NOP,                // Undo/redo will ignore this entry.  Only forces the start of a new stack
+    CHANGED,            // params of items have a value changed: undo is made by exchange
+                        // values with a copy of these values
+    NEWITEM,            // new item, undo by changing in deleted
+    DELETED,            // deleted item, undo by changing in deleted
+    LIBEDIT,            // Specific to the component editor (symbol_editor creates a full copy
+                        // of the current component when changed)
+    LIB_RENAME,         // As LIBEDIT, but old copy should be removed from library
+    EXCHANGE_T,         // Use for changing the schematic text type where swapping
+                        // data structure is insufficient to restore the change.
+    DRILLORIGIN,        // origin changed (like CHANGED, contains the origin and a copy)
+    GRIDORIGIN,         // origin changed (like CHANGED, contains the origin and a copy)
+    PAGESETTINGS,       // page settings or title block changes
+    REGROUP,            // new group of items created (do not use GROUP to avoid collision
+                        // with an header on msys2)
+    UNGROUP             // existing group destroyed (items not destroyed)
 };
 
 
diff --git a/pcbnew/tools/group_tool.cpp b/pcbnew/tools/group_tool.cpp
index 12735b42ba..748ded0c89 100644
--- a/pcbnew/tools/group_tool.cpp
+++ b/pcbnew/tools/group_tool.cpp
@@ -279,10 +279,10 @@ int GROUP_TOOL::Group( const TOOL_EVENT& aEvent )
         for( EDA_ITEM* item : selection )
         {
             group->AddItem( static_cast<BOARD_ITEM*>( item ) );
-            undoList.PushItem( ITEM_PICKER( nullptr, item, UNDO_REDO::GROUP ) );
+            undoList.PushItem( ITEM_PICKER( nullptr, item, UNDO_REDO::REGROUP ) );
         }
 
-        m_frame->SaveCopyInUndoList( undoList, UNDO_REDO::GROUP );
+        m_frame->SaveCopyInUndoList( undoList, UNDO_REDO::REGROUP );
     }
 
     selTool->ClearSelection();
diff --git a/pcbnew/undo_redo.cpp b/pcbnew/undo_redo.cpp
index 0f7f26792d..70674684e0 100644
--- a/pcbnew/undo_redo.cpp
+++ b/pcbnew/undo_redo.cpp
@@ -284,7 +284,7 @@ void PCB_BASE_EDIT_FRAME::SaveCopyInUndoList( const PICKED_ITEMS_LIST& aItemsLis
         case UNDO_REDO::NEWITEM:
         case UNDO_REDO::DELETED:
         case UNDO_REDO::PAGESETTINGS:
-        case UNDO_REDO::GROUP:
+        case UNDO_REDO::REGROUP:
         case UNDO_REDO::UNGROUP:
             break;
 
@@ -489,13 +489,13 @@ void PCB_BASE_EDIT_FRAME::PutDataInPreviousState( PICKED_ITEMS_LIST* aList )
 
             break;
 
-        case UNDO_REDO::GROUP:
+        case UNDO_REDO::REGROUP:
             aList->SetPickedItemStatus( UNDO_REDO::UNGROUP, ii );
             static_cast<BOARD_ITEM*>( eda_item )->SetParentGroup( nullptr );
             break;
 
         case UNDO_REDO::UNGROUP:
-            aList->SetPickedItemStatus( UNDO_REDO::GROUP, ii );
+            aList->SetPickedItemStatus( UNDO_REDO::REGROUP, ii );
 
             if( group )
                 group->AddItem( static_cast<BOARD_ITEM*>( eda_item ) );