Hi, I was trying to build GiNaC 1.5.1 with cln 1.1.8. I ran into the following two problems: configure did not substitute correctly @CPPFLAGS@: [stefanw@localhost ginac-1.5.1]$ make Making all in ginac make[1]: Entering directory `/home/stefanw/build/ginac-1.5.1/ginac' make all-am make[2]: Entering directory `/home/stefanw/build/ginac-1.5.1/ginac' /bin/sh ../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I. -I../config @CPPFLAGS -I/home/stefanw/add/cln/include -g -O2 -MT add.lo -MD -MP -MF .deps/add.Tpo -c -o add.lo add.cpp libtool: compile: g++ -DHAVE_CONFIG_H -I. -I../config @CPPFLAGS -I/home/stefanw/add/cln/include -g -O2 -MT add.lo -MD -MP -MF .deps/add.Tpo -c add.cpp -fPIC -DPIC -o .libs/add.o g++: @CPPFLAGS: No such file or directory make[2]: *** [add.lo] Error 1 make[2]: Leaving directory `/home/stefanw/build/ginac-1.5.1/ginac' make[1]: *** [all] Error 2 make[1]: Leaving directory `/home/stefanw/build/ginac-1.5.1/ginac' make: *** [all-recursive] Error 1 Makefile: CLN_CFLAGS = @CPPFLAGS -I/home/stefanw/add/cln/include CPPFLAGS = @CPPFLAGS -I/home/stefanw/add/cln/include Makefile.in: CLN_CFLAGS = @CLN_CFLAGS@ CPPFLAGS = @CPPFLAGS@ Fixing this, I ran into the second problem: polynomial/mod_gcd.cpp: In function `void GiNaC::find_next_prime(cln::cl_I&, const cln::cl_I&)': polynomial/mod_gcd.cpp:109: error: no match for 'operator++' in '++p' polynomial/mod_gcd.cpp: In function `void GiNaC::mod_gcd(GiNaC::upoly&, GiNaC::upoly, GiNaC::upoly)': polynomial/mod_gcd.cpp:137: error: no match for 'operator<<=' in 'p <<= 1' make[2]: *** [mod_gcd.lo] Error 1 I then switched to cln-1.2.2, and everything went smooth. I would suggest to raise in configure.ac the requirement on the version number of cln (currently it's 1.1.6). Best wishes, Stefan