-AC_CHECK_FUNCS(nanosleep, [], AC_CHECK_LIB(rt, nanosleep, [nanosleep_needs_rt="yes"], AC_MSG_ERROR(cannot find nanosleep)))
+nanosleep_needs_posix4="no"
+AC_CHECK_FUNCS(nanosleep,
+ [],
+ AC_CHECK_LIB(rt, nanosleep,
+ [nanosleep_needs_rt="yes"],
+ AC_CHECK_LIB(posix4, nanosleep,
+ [nanosleep_needs_posix4="yes"],
+ AC_MSG_ERROR(cannot find nanosleep))))