diff --git a/acinclude.m4 b/acinclude.m4
new file mode 100644
index 0000000..db8b82f
--- /dev/null
+++ b/acinclude.m4
@@ -0,0 +1,17 @@
+dnl check for fields in a structure
+dnl
+dnl AC_HAVE_STRUCT_FIELD(struct, field, headers)
+
+AC_DEFUN(AC_HAVE_STRUCT_FIELD, [
+define(cache_val, translit(ac_cv_type_$1_$2, [A-Z ], [a-z_]))
+AC_CACHE_CHECK([for $2 in $1], cache_val,[
+AC_TRY_COMPILE([$3],[$1 x; x.$2;],
+cache_val=yes,
+cache_val=no)])
+if test "$cache_val" = yes; then
+	define(foo, translit(HAVE_$1_$2, [a-z ], [A-Z_]))
+	AC_DEFINE(foo, 1, [Define if $1 has field $2.])
+	undefine(foo)
+fi
+undefine(cache_val)
+])