diff --git a/src/core/window.c b/src/core/window.c
index eaae5b0fc..32c946192 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -3622,6 +3622,13 @@ meta_window_activate_full (MetaWindow     *window,
                            MetaWorkspace  *workspace)
 {
   gboolean allow_workspace_switch;
+
+  if (window->unmanaging)
+    {
+      g_warning ("Trying to activate unmanaged window '%s'", window->desc);
+      return;
+    }
+
   meta_topic (META_DEBUG_FOCUS,
               "_NET_ACTIVE_WINDOW message sent for %s at time %u "
               "by client type %u.\n",