I noticed today that the current CVS head won't compile on Solaris and it looks like it is due to a configure change around the end of April. This change happened between version 1.211 and 1.212 and is the check for sockaddr_storage. The script seems to assume that this struct is defined in /usr/include/netinet/in.h, but on Solaris and maybe other OSs it isn't located there, but in /usr/include/sys/socket.h. Google shows a few ways of doing this, but this link shows what might be the closest to what you currently do http://article.gmane.org/gmane.comp.web.curl.cvs/4598 and it is doing dnl Check for struct sockaddr_storage. Most IPv6-enabled hosts have it, but dnl AIX 4.3 is one known exception. [in acinclude.m4] AC_DEFUN([TYPE_SOCKADDR_STORAGE], [ AC_CHECK_TYPE([struct sockaddr_storage], AC_DEFINE(HAVE_STRUCT_SOCKADDR_STORAGE, 1, [if struct sockaddr_storage is defined]), , [ #ifdef HAVE_SYS_TYPES_H #include <sys/types.h> #endif #ifdef HAVE_SYS_SOCKET_H #include <sys/socket.h> #endif #ifdef HAVE_NETINET_IN_H #include <netinet/in.h> #endif #ifdef HAVE_ARPA_INET_H #include <arpa/inet.h> #endif ]) ]) [in configure.ac] TYPE_SOCKADDR_STORAGE If that looks about right I can give it a test and submit a patch. Is it safe to modify acinclude.m4? -jason