Checking if your kit is complete... Looks good 'LICENSE' is not a known MakeMaker parameter name. Note (probably harmless): No library found for -lfftw3 Writing Makefile for Math::FFTW cp lib/Math/FFTW.pm blib/lib/Math/FFTW.pm /home/cpanrun/build/5.6.1/bin/perl -I/home/cpanrun/build/5.6.1/lib/5.6.1/i686-linux-thread-multi -I/home/cpanrun/build/5.6.1/lib/5.6.1 /home/cpanrun/build/5.6.1/lib/5.6.1/ExtUtils/xsubpp -typemap /home/cpanrun/build/5.6.1/lib/5.6.1/ExtUtils/typemap FFTW.xs > FFTW.xsc && mv FFTW.xsc FFTW.c Please specify prototyping behavior for FFTW.xs (see perlxs manual) gcc -c -I. -DUSE_REENTRANT_API -D_GNU_SOURCE -D_REENTRANT -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -DVERSION=\"0.01\" -DXS_VERSION=\"0.01\" -fpic -I/home/cpanrun/build/5.6.1/lib/5.6.1/i686-linux-thread-multi/CORE FFTW.c FFTW.xs:4: fftw3.h: No such file or directory make: *** [FFTW.o] Error 1