Dear all, when trying to rebuild ghc-6.4 from source, I fall into following error: ........ gcc -O -I../../includes -Wall -c Shade.c -o Shade.o gcc -O -I../../includes -Wall -c TopTwenty.c -o TopTwenty.o gcc -O -I../../includes -Wall -c TraceElement.c -o TraceElement.o gcc -O -I../../includes -Wall -c Utilities.c -o Utilities.o gcc -o hp2ps -O -I../../includes -Wall AreaBelow.o AuxFile.o Axes.o Curves.o Deviation.o DimensiDeviation.o(.text+0x316): In function `Deviation': : undefined reference to `sqrt' collect2: ld returned 1 exit status make[3]: *** [hp2ps] Error 1 make[2]: *** [all] Error 1 make[1]: *** [all] Error 1 make[1]: Leaving directory `/root/build/ghc-6.4/ghc' make: *** [build] Error 1 When building, I followed recommendations from http://www.haskell.org/ghc/docs/latest/html/building/sec-building-from-sourc... That said, I did: autoreconf ./configure --prefix=/opt/ghc64 make My OS is Linux, kernel 2.6.9 GCC version is 3.3.2 Perl version is 5.8.3 Could you please advice? Thanks in advance, Vadim.