--- a/bindings/ruby/tomoe-rb-char.c
+++ b/bindings/ruby/tomoe-rb-char.c
@@ -2,6 +2,10 @@
 
 #define _SELF(obj) RVAL2TCHR(obj)
 
+#ifndef RSTRING_LEN
+# define RSTRING_LEN(s) (RSTRING(s)->len)
+#endif
+
 static VALUE
 tc_initialize(int argc, VALUE *argv, VALUE self)
 {
@@ -13,7 +17,7 @@
     if (NIL_P(xml)) {
         chr = tomoe_char_new();
     } else {
-        chr = tomoe_char_new_from_xml_data(RVAL2CSTR(xml), RSTRING(xml)->len);
+        chr = tomoe_char_new_from_xml_data(RVAL2CSTR(xml), RSTRING_LEN(xml));
     }
 
     G_INITIALIZE(self, chr);
--- a/macros/ruby.m4
+++ b/macros/ruby.m4
@@ -28,13 +28,18 @@
 
   changequote(<<, >>)
   for var_name in archdir sitearchdir CFLAGS LIBRUBYARG libdir \
-                  sitelibdir sitearchdir; do
-    rbconfig_tmp=`$rbconfig "print Config::CONFIG['$var_name']"`
+                  sitelibdir rubyhdrdir rubyarchhdrdir; do
+    rbconfig_tmp=`$rbconfig "print RbConfig::CONFIG['$var_name']"`
     eval "rbconfig_$var_name=\"$rbconfig_tmp\""
   done
   changequote([, ])
 
-  RUBY_CFLAGS="$RUBY_CFLAGS -I$rbconfig_archdir "
+  if test "x$rbconfig_rubyhdrdir" = "x"; then
+    RUBY_CFLAGS="$RUBY_CFLAGS -I$rbconfig_archdir "
+  else
+    RUBY_CFLAGS="$RUBY_CFLAGS -I$rbconfig_rubyhdrdir "
+    RUBY_CFLAGS="$RUBY_CFLAGS -I$rbconfig_rubyarchhdrdir "
+  fi
   RUBY_CFLAGS="$RUBY_CFLAGS -I$rbconfig_sitearchdir "
   RUBY_CFLAGS="$RUBY_CFLAGS $rbconfig_CFLAGS "
   RUBY_LIBS="$rbconfig_LIBRUBYARG"
--- a/module/dict/tomoe-dict-ruby.c
+++ b/module/dict/tomoe-dict-ruby.c
@@ -52,6 +52,13 @@
 #define TOMOE_IS_DICT_RUBY_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), TOMOE_TYPE_DICT_RUBY))
 #define TOMOE_DICT_RUBY_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS((obj), TOMOE_TYPE_DICT_RUBY, TomoeDictRubyClass))
 
+#ifndef RARRAY_LEN
+# define RARRAY_LEN(a) (RARRAY(a)->len)
+#endif
+#ifndef RARRAY_PTR
+# define RARRAY_PTR(a) (RARRAY(a)->ptr)
+#endif
+
 enum {
     PROP_0,
     PROP_FILENAME,
@@ -209,7 +216,7 @@
         ruby_script (PACKAGE);
         ruby_set_argv (1, argv);
 
-        if (RARRAY(rb_load_path)->len == 0) {
+        if (RARRAY_LEN(rb_load_path) == 0) {
             ruby_init_loadpath ();
         }
     }
@@ -405,10 +412,10 @@
 
     rb_results = rb_funcall (dict->rb_dict, rb_intern ("search"),
                              1, GOBJ2RVAL (query));
-    len = RARRAY (rb_results)->len;
+    len = RARRAY_LEN(rb_results);
     for (i = len; i; i--) {
         results = g_list_prepend (results,
-                                  RVAL2TCND (RARRAY (rb_results)->ptr[i]));
+                                  RVAL2TCND (RARRAY_PTR(rb_results)[i]));
     }
     return results;
 }