diff --git a/misc/schema/xrc_schema.rnc b/misc/schema/xrc_schema.rnc
index 4986ea6efb..cf6f68a656 100644
--- a/misc/schema/xrc_schema.rnc
+++ b/misc/schema/xrc_schema.rnc
@@ -1492,13 +1492,17 @@ wxSizer_item =
         ) &
         stdObjectNodeAttributes &
         [xrc:p="o"] element option   {_, t_integer }* &
-        [xrc:p="o"] element flag     {_, t_style }* &
         [xrc:p="o"] element border   {_, t_dimension }* &
         [xrc:p="o"] element minsize  {_, t_size }* &
         [xrc:p="o"] element ratio    {_, t_size }* &
         # TODO: cell{pos,span} are wxGridBagSizer-only and required in it, this is too lax
         [xrc:p="o"] element cellpos  {_, t_position }* &
-        [xrc:p="o"] element cellspan {_, t_size }*
+        [xrc:p="o"] element cellspan {_, t_size }* &
+        [xrc:p="o"] element flag     {_,
+            xsd:string {
+                pattern = "(wxLEFT|wxRIGHT|wxTOP|wxBOTTOM|wxNORTH|wxSOUTH|wxEAST|wxWEST|wxALL|wxGROW|wxEXPAND|wxSHAPED|wxSTRETCH_NOT|wxALIGN_CENTER|wxALIGN_CENTRE|wxALIGN_LEFT|wxALIGN_RIGHT|wxALIGN_TOP|wxALIGN_BOTTOM|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTRE_HORIZONTAL|wxALIGN_CENTER_VERTICAL|wxALIGN_CENTRE_VERTICAL)( *\| *(wxLEFT|wxRIGHT|wxTOP|wxBOTTOM|wxNORTH|wxSOUTH|wxEAST|wxWEST|wxALL|wxGROW|wxEXPAND|wxSHAPED|wxSTRETCH_NOT|wxALIGN_CENTER|wxALIGN_CENTRE|wxALIGN_LEFT|wxALIGN_RIGHT|wxALIGN_TOP|wxALIGN_BOTTOM|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTRE_HORIZONTAL|wxALIGN_CENTER_VERTICAL|wxALIGN_CENTRE_VERTICAL))*"
+            }
+        }*
     }
 
 wxBoxSizer =