I am trying to compile Perl 5.12.1 in my home directory on Red Hat Enterprise Linux 5.5. However, when I try to make, I eventually receive the following error: Making IO (all) make[1]: Entering directory `/users/rmi1/build/perl-5.12.0/dist/IO' make[1]: Leaving directory `/users/rmi1/build/perl-5.12.0/dist/IO' Making all in dist/IO make all PERL_CORE=1 LIBPERL_A=libperl.a LINKTYPE=dynamic make[1]: Entering directory `/users/rmi1/build/perl-5.12.0/dist/IO' cc -c -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -DVERSION=\"1.25_02\" -DXS_VERSION=\"1.25_02\" -fPIC "-I../.." IO.c IO.xs: In function ‘XS_IO__Poll__poll’: IO.xs:249: error: invalid application of ‘sizeof’ to incomplete type ‘struct pollfd’ IO.xs:253: error: invalid use of undefined type ‘struct pollfd’ IO.xs:253: error: dereferencing pointer to incomplete type IO.xs:255: error: invalid use of undefined type ‘struct pollfd’ IO.xs:255: error: dereferencing pointer to incomplete type IO.xs:257: error: invalid use of undefined type ‘struct pollfd’ IO.xs:257: error: dereferencing pointer to incomplete type IO.xs:261: error: invalid use of undefined type ‘struct pollfd’ IO.xs:261: error: dereferencing pointer to incomplete type IO.xs:262: error: invalid use of undefined type ‘struct pollfd’ IO.xs:262: error: dereferencing pointer to incomplete type make[1]: *** [IO.o] Error 1 make[1]: Leaving directory `/users/rmi1/build/perl-5.12.0/dist/IO' Unsuccessful make(dist/IO): code=512 at make_ext.pl line 449. make: *** [lib/auto/IO/IO.so] Error 2 What could be causing this?