diff --git a/src/frames/meta-frame-header.c b/src/frames/meta-frame-header.c
index 5f2cda1c5..e5b0b5b9f 100644
--- a/src/frames/meta-frame-header.c
+++ b/src/frames/meta-frame-header.c
@@ -115,6 +115,8 @@ meta_frame_header_init (MetaFrameHeader *content)
   GtkWidget *header_bar;
 
   header_bar = gtk_header_bar_new ();
+  gtk_widget_add_css_class (header_bar, "titlebar");
+  gtk_widget_add_css_class (header_bar, "default-decoration");
   gtk_widget_insert_before (header_bar, GTK_WIDGET (content), NULL);
 }
 
diff --git a/src/frames/meta-frame.c b/src/frames/meta-frame.c
index 7b55e74e5..66f2109c3 100644
--- a/src/frames/meta-frame.c
+++ b/src/frames/meta-frame.c
@@ -228,6 +228,7 @@ meta_frame_new (Window window)
   header = meta_frame_header_new ();
 
   gtk_window_set_titlebar (GTK_WINDOW (frame), header);
+  gtk_widget_add_css_class (frame, "default-decoration");
 
   content = meta_frame_content_new (window);
   gtk_window_set_child (GTK_WINDOW (frame), content);