--- a/configure.in
+++ b/configure.in
@@ -52,7 +52,7 @@
 AC_HEADER_STDC
 AC_PATH_XTRA 
 
-if test "x${ac_cv_have_x:0:10}" != "xhave_x=yes"; then
+if test "x$have_x" != "xyes"; then
 	AC_MSG_ERROR([X11 is missing but required.])
 fi