diff --git a/gtk/gtkrenderborder.c b/gtk/gtkrenderborder.c
index f533a0cb6c..8271b22769 100644
--- a/gtk/gtkrenderborder.c
+++ b/gtk/gtkrenderborder.c
@@ -247,7 +247,7 @@ gtk_border_image_compute_slice_size (GtkBorderImageSliceSize sizes[3],
   sizes[1].offset = sizes[0].size;
 }
 
-void
+static void
 gtk_border_image_render (GtkBorderImage   *image,
                          const double      border_width[4],
                          cairo_t          *cr,