Index: m4/ax_pthread.m4 =================================================================== --- m4/ax_pthread.m4 (revision 1204663) +++ m4/ax_pthread.m4 (working copy) @@ -256,14 +256,7 @@ flag=no case "${host_cpu}-${host_os}" in *-aix* | *-freebsd* | *-darwin*) flag="-D_THREAD_SAFE";; - *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";; + *-osf* | *-hpux*) flag="-D_REENTRANT";; + *solaris*) + if test "$GCC" = "yes"; then + flag="-D_REENTRANT" + else + flag="-mt -D_REENTRANT" + fi + ;; esac AC_MSG_RESULT(${flag}) if test "x$flag" != xno; then