diff --git a/gtk/gtkprinter.h b/gtk/gtkprinter.h
index 1eb5bd1bf9..e3c8dd71b7 100644
--- a/gtk/gtkprinter.h
+++ b/gtk/gtkprinter.h
@@ -67,7 +67,7 @@ struct _GtkPrinter
 {
   GObject parent_instance;
 
-  GtkPrinterPrivate *priv;
+  GtkPrinterPrivate *GSEAL (priv);
 };
 
 struct _GtkPrinterClass