Hello, On my Fedora 13 x86-64 system, $ env | grep CC CC=ccache gcc $ ./configure --prefix=/usr --libdir=/usr/lib64 [...] Checking for getline... No (will use our own instead). Checking for strcasestr... No (will use our own instead). Checking for rpath support... No (nothing to worry about). Checking for -Wl,--as-needed... No (nothing to worry about). [... success ...] The replacement strcasestr later causes build errors: CXX -O2 lib/directory.o In file included from lib/notmuch-private.h:41, from lib/directory.cc:22: /usr/include/string.h:371: error: new declaration ‘const char* strcasestr(const char*, const char*)’ compat/compat.h:46: error: ambiguates old declaration ‘char* strcasestr(const char*, const char*)’ But if I export CC=gcc, things succeed: Checking for getline... Yes. Checking for strcasestr... Yes. Checking for rpath support... Yes. And the build goes fine. I think the problem occurs due to the IFS setting in configure. Not sure what the right solution is; I am not married to having ccache in the environment. It's simply that this is what has worked in the past. If there is a better option for using ccache I'm happy to switch, as long as it's globally applicable. Happy hacking, Andy