Linking external libraries with EXTRALIBS

Hi, I’m not sure if this is the right forum to ask this question, but the others didn’t seem to fit it.

I’m trying to include an external library (gsl) in the compilation of my Geant4 program. According to the users guide for application developers this should be done by adding a line (according to the user guide for application developers)

EXTRALIBS += -lgsl -lgslcblas

But this has no effect. When I compile the linker complains about undefined references to functions from the gsl library, and running make VERBOSE=1 shows that the EXTRALIBS are not included in the compile command at all.

This is using CentOS 6 with gcc 9.1.0 and geant4.10.5.p01.