diff --git a/xed/xed-panel.c b/xed/xed-panel.c
index 2877c38..81cab98 100644
--- a/xed/xed-panel.c
+++ b/xed/xed-panel.c
@@ -364,15 +364,15 @@ xed_panel_constructor (GType                  type,
     build_notebook_for_panel (panel);
     gtk_box_pack_start (GTK_BOX (panel->priv->main_box), panel->priv->notebook, TRUE, TRUE, 0);
 
-    gtk_style_context_add_class (gtk_widget_get_style_context (panel), "xed-panel");
+    gtk_style_context_add_class (gtk_widget_get_style_context (GTK_WIDGET (panel)), "xed-panel");
 
     if (panel->priv->orientation == GTK_ORIENTATION_VERTICAL)
     {
-        gtk_style_context_add_class (gtk_widget_get_style_context (panel), "side");
+        gtk_style_context_add_class (gtk_widget_get_style_context (GTK_WIDGET (panel)), "side");
     }
     else
     {
-        gtk_style_context_add_class (gtk_widget_get_style_context (panel), "bottom");
+        gtk_style_context_add_class (gtk_widget_get_style_context (GTK_WIDGET (panel)), "bottom");
     }
 
     return obj;