diff --git a/gtk/gtkviewport.c b/gtk/gtkviewport.c
index 048d0f63cf..73238ee8b8 100644
--- a/gtk/gtkviewport.c
+++ b/gtk/gtkviewport.c
@@ -328,9 +328,14 @@ viewport_get_view_allocation (GtkViewport   *viewport,
 
   context = gtk_widget_get_style_context (widget);
   state = gtk_widget_get_state_flags (widget);
+  gtk_style_context_save (context);
+  gtk_style_context_add_class (context, GTK_STYLE_CLASS_FRAME);
+
   gtk_style_context_get_padding (context, state, &padding);
   gtk_style_context_get_border (context, state, &border);
 
+  gtk_style_context_restore (context);
+
   if (priv->shadow_type != GTK_SHADOW_NONE)
     {
       view_allocation->x = border.left;