Found this while valgrinding eog:

==14443== 128 bytes in 1 blocks are definitely lost in loss record 8,506 of 10,240
==14443==    at 0x4C2853F: realloc (vg_replace_malloc.c:525)
==14443==    by 0xCC87490: g_realloc (gmem.c:233)
==14443==    by 0xCCA258E: g_string_maybe_expand (gstring.c:401)
==14443==    by 0xCCA2C76: g_string_insert_len (gstring.c:741)
==14443==    by 0xCC6D401: g_build_path_va (gfileutils.c:1488)
==14443==    by 0xCC6EAD8: g_build_filename (gfileutils.c:1758)
==14443==    by 0x65A3F29: gtk_css_provider_get_named (gtkcssprovider.c:4207)
==14443==    by 0x669F50A: settings_update_key_theme (gtksettings.c:2762)
==14443==    by 0x66A0AD6: gtk_settings_get_for_screen (gtksettings.c:1438)
==14443==    by 0x664C561: display_opened_cb (gtkmodules.c:479)
==14443==    by 0xBFC4E89: g_closure_invoke (gclosure.c:767)
==14443==    by 0xBFD7451: signal_emit_unlocked_R (gsignal.c:3252)
==14443==    by 0xBFE0F58: g_signal_emit_valist (gsignal.c:2983)
==14443==    by 0xBFE12C1: g_signal_emit_by_name (gsignal.c:3077)
==14443==    by 0x6D6772D: _gdk_x11_display_open (gdkdisplay-x11.c:1414)
==14443==    by 0x6D64F43: gdk_x11_display_manager_open_display (gdkdisplaymanager-x11.c:55)
==14443==    by 0x662BD76: post_parse_hook (gtkmain.c:893)
==14443==    by 0xCC8D3F8: g_option_context_parse (goption.c:1952)
==14443==    by 0x41F4E5: main (main.c:210)