This has happened before but I can't remember the reason. After updating gcc (4.8.4 to 2.9.2) on a Gentoo build host, the Haiku configure script fails with: checking for TLS support... yes checking for library containing clock_gettime... none required checking for gmp.h... no configure: error: gmp.h can't be found, or is unusable. Makefile:4734: recipe for target 'configure-mpfr' failed Rebuilding the gmp and mpc packages doesn't help. What does? Michael.