diff --git a/src/core/window.c b/src/core/window.c
index 78faf381c..a584c1f55 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -3639,6 +3639,13 @@ meta_window_activate_full (MetaWindow     *window,
 {
   MetaWorkspaceManager *workspace_manager = window->display->workspace_manager;
   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",