diff --git a/cf/check-xau.m4 b/cf/check-xau.m4
index ce512d65a..2d192f38f 100644
--- a/cf/check-xau.m4
+++ b/cf/check-xau.m4
@@ -11,13 +11,43 @@ LIBS="$X_PRE_LIBS $X_EXTRA_LIBS $LIBS"
 save_LDFLAGS="$LDFLAGS"
 LDFLAGS="$LDFLAGS $X_LIBS"
 
-AC_FIND_FUNC_NO_LIBS(XauReadAuth, Xau X11)
-ac_xxx="$LIBS"
-LIBS="$LIB_XauReadAuth $LIBS"
-AC_CHECK_FUNCS(XauWriteAuth)
-LIBS="$ac_xxx"
-AM_CONDITIONAL(NEED_WRITEAUTH, test "$ac_cv_func_XauWriteAuth" != "yes")
+## check for XauWriteAuth first, so we detect the case where
+## XauReadAuth is in -lX11, but XauWriteAuth is only in -lXau this
+## could be done by checking for XauReadAuth in -lXau first, but this
+## breaks in IRIX 6.5
 
+AC_FIND_FUNC_NO_LIBS(XauWriteAuth, X11 Xau)
+ac_xxx="$LIBS"
+LIBS="$LIB_XauWriteAuth $LIBS"
+AC_FIND_FUNC_NO_LIBS(XauReadAuth, X11 Xau)
+LIBS="$ac_xxx"
+
+## set LIB_XauReadAuth to union of these tests, since this is what the
+## Makefiles are using
+case "$ac_cv_funclib_XauWriteAuth" in
+yes)	;;
+no)	;;
+*)	if test "$ac_cv_funclib_XauReadAuth" = yes; then
+		LIB_XauReadAuth="$LIB_XauWriteAuth"
+	else
+		LIB_XauReadAuth="$LIB_XauReadAuth $LIB_XauWriteAuth"
+	fi
+	;;
+esac
+
+if test "$AUTOMAKE" != ""; then
+	AM_CONDITIONAL(NEED_WRITEAUTH, test "$ac_cv_func_XauWriteAuth" != "yes")
+else
+	AC_SUBST(NEED_WRITEAUTH_TRUE)
+	AC_SUBST(NEED_WRITEAUTH_FALSE)
+	if test "$ac_cv_func_XauWriteAuth" != "yes"; then
+		NEED_WRITEAUTH_TRUE=
+		NEED_WRITEAUTH_FALSE='#'
+	else
+		NEED_WRITEAUTH_TRUE='#'
+		NEED_WRITEAUTH_FALSE=
+	fi
+fi
 CFLAGS=$save_CFLAGS
 LIBS=$save_LIBS
 LDFLAGS=$save_LDFLAGS