diff --git a/Documentation/Examples/cascade_example.cc b/Documentation/Examples/cascade_example.cc
index 399277cb4dd010b0482f938939a32ed424080f1f..6821e510c5b253198775bafecdd429d457636d83 100644
--- a/Documentation/Examples/cascade_example.cc
+++ b/Documentation/Examples/cascade_example.cc
@@ -25,6 +25,8 @@
 
 #include <corsika/units/PhysicalUnits.h>
 
+//#include <corsika/units/PhysicalConstants.h>
+#include <corsika/units/PhysicalUnits.h>
 using namespace corsika;
 using namespace corsika::process;
 using namespace corsika::units;