diff --git a/gtk/gtkapplicationprivate.h b/gtk/gtkapplicationprivate.h
index a6c56c89df..4b4e63896f 100644
--- a/gtk/gtkapplicationprivate.h
+++ b/gtk/gtkapplicationprivate.h
@@ -160,7 +160,7 @@ GType                   gtk_application_impl_quartz_get_type            (void);
 GtkApplicationImpl *    gtk_application_impl_new                        (GtkApplication              *application,
                                                                          GdkDisplay                  *display);
 void                    gtk_application_impl_startup                    (GtkApplicationImpl          *impl,
-                                                                         gboolean                     register_sesion);
+                                                                         gboolean                     register_session);
 void                    gtk_application_impl_shutdown                   (GtkApplicationImpl          *impl);
 void                    gtk_application_impl_before_emit                (GtkApplicationImpl          *impl,
                                                                          GVariant                    *platform_data);