diff -up ./gtk/gtksettings.c.defaulttheme ./gtk/gtksettings.c
--- ./gtk/gtksettings.c.defaulttheme	2014-09-29 23:02:17.000000000 +0300
+++ ./gtk/gtksettings.c	2014-10-24 19:09:04.575581595 +0300
@@ -331,7 +331,7 @@ gtk_settings_class_init (GtkSettingsClas
                                              g_param_spec_string ("gtk-fallback-icon-theme",
 								  P_("Fallback Icon Theme Name"),
 								  P_("Name of a icon theme to fall back to"),
-								  NULL,
+								  "Adwaita",
 								  GTK_PARAM_READWRITE),
                                              NULL);
   g_assert (result == PROP_FALLBACK_ICON_THEME);