diff --git a/pub/lib/obj.hpp b/pub/lib/obj.hpp
index 8eeab0909d57526e7d2133f846c1e206bd9f4273..e3910b60e21fc4e5085ad7de6f297e1eda650c53 100644
--- a/pub/lib/obj.hpp
+++ b/pub/lib/obj.hpp
@@ -7,6 +7,8 @@
 //! \file  obj.hpp
 //! \brief Data containers: CObj and its children.
 
+#include <cmath>
+
 //! Generic data container, pure virtual base class.
 
 class CObj {