--- lib/EWMH.cc~	2020-02-11 13:24:59.000000000 +0100
+++ lib/EWMH.cc	2020-11-20 18:22:46.000000000 +0100
@@ -24,6 +24,7 @@
 
 #include "EWMH.hh"
 
+#include <stdlib.h>
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>