--- Makefile	2011-10-17 16:43:21.000000000 +0200
+++ Makefile.new	2014-12-08 18:51:42.905040422 +0100
@@ -1,6 +1,6 @@
 CC = gcc
 CFLAGS = -Wall -ggdb
-CFLAGS = -Wall -O3 -ffast-math -fomit-frame-pointer
+CFLAGS = -Wall -O3 -ffast-math -fomit-frame-pointer -lm
 
 LDFLAGS += -L/home/cro/fftw/lib
 CFLAGS += -I/home/cro/fftw/include