--- fluxbox-1.3.7.orig/src/FbTk/XftFontImp.cc	2015-02-08 11:44:45.000000000 +0100
+++ fluxbox-1.3.7/src/FbTk/XftFontImp.cc	2015-06-03 09:16:38.000000000 +0200
@@ -23,6 +23,7 @@
 #include "App.hh"
 #include "FbDrawable.hh"
 
+#include <cstdlib>
 #include <cmath>
 #include <cstdio>
 #include <algorithm>