I'm using CentOS 5.4 32 bits and since squid version 3.1.5 I'm getting some errors when making the sources. Since of that release, I have to edit some header files to make the sources. Follow my steps to solve the problem. File: libltdl/libltdl/lt_error.h Modification1: Change all the include <FILE> for include "FILE" Modification2: Change the line #include "libltdl/lt_system.h" for #include "lt_system.h" File: libltdl/libltdl/lt_dlloader.h Modification1: Change all the include <FILE> for include "FILE" Modification2: Change the line #include "libltdl/lt_system.h" for #include "lt_system.h" File: libltdl/libltdl/lt_system.h Modification: Change all the include <FILE> for include "FILE"