diff --git a/src/x11/meta-x11-selection.c b/src/x11/meta-x11-selection.c
index e55a1995d..8f068dedc 100644
--- a/src/x11/meta-x11-selection.c
+++ b/src/x11/meta-x11-selection.c
@@ -32,13 +32,6 @@
 #define UTF8_STRING_MIMETYPE "text/plain;charset=utf-8"
 #define STRING_MIMETYPE "text/plain"
 
-/* Set an arbitrary (although generous) threshold to determine whether a
- * XFixesSelectionNotify corresponds to a XSetSelectionOwner from another
- * client. The selection timestamp is not updated if the owner client is
- * closed.
- */
-#define SELECTION_CLEARED_BY_CLIENT(e) (e->timestamp - e->selection_timestamp < 50)
-
 static gboolean
 atom_to_selection_type (Display           *xdisplay,
                         Atom               selection,
@@ -342,7 +335,7 @@ meta_x11_selection_handle_xfixes_selection_notify (MetaX11Display *x11_display,
 
   if (event->owner == None && x11_display->selection.owners[selection_type])
     {
-      if (SELECTION_CLEARED_BY_CLIENT (event))
+      if (event->subtype == XFixesSetSelectionOwnerNotify)
         {
           MetaSelectionSource *source;