Index: include/animorph/util.h
--- include/animorph/util.h.orig
+++ include/animorph/util.h
@@ -32,6 +32,7 @@
   #include <config.h>
 #endif
 
+#include <cstdlib>
 #include <string>
 #include <sstream>
 #include <iomanip>
