diff -ruN panel-plugin.orig/pulseaudio-button.c panel-plugin/pulseaudio-button.c
--- panel-plugin.orig/pulseaudio-button.c	2015-03-19 00:00:00.000000000 +0100
+++ panel-plugin/pulseaudio-button.c	2015-03-19 00:00:00.000000000 +0100
@@ -288,7 +288,7 @@
     {
       if (GDK_IS_PIXBUF (button->pixbufs[i]))
         g_object_unref (G_OBJECT (button->pixbufs[i]));
-        info = gtk_icon_theme_lookup_icon (gtk_icon_theme_get_default (), icons[i], button->icon_size, GTK_ICON_LOOKUP_USE_BUILTIN);
+        info = gtk_icon_theme_lookup_icon (gtk_icon_theme_get_default (), icons[i], button->icon_size, GTK_ICON_LOOKUP_GENERIC_FALLBACK);
         button->pixbufs[i] = gtk_icon_info_load_symbolic_for_context (info, context, NULL, NULL);
     }