Hello, It seems that the call to gSystem->Load("someLib") behaves differently if done within a macro than when done directly in the interpreter: Loading with macro $ root -b reproducer.C Processing math_convert_reproducer.C... IncrementalExecutor::executeFunction: symbol '_ZN4ROOT4Math9gv_detail7c…

For ROOT 6, just in the beginning of your file, add: R__LOAD_LIBRARY(libGenVector)

Thanks that seems to do the trick!