diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index cddf22772c..eaf0b5729c 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -7138,6 +7138,9 @@ gtk_window_has_mnemonic_modifier_pressed (GtkWindow *window)
   GdkDeviceManager *device_manager;
   gboolean retval = FALSE;
 
+  if (!window->priv->mnemonic_modifier)
+    return FALSE;
+
   device_manager = gdk_display_get_device_manager (gtk_widget_get_display (GTK_WIDGET (window)));
   devices = gdk_device_manager_list_devices (device_manager, GDK_DEVICE_TYPE_MASTER);