Index: graphviz-2.38.0/config/config_ruby.rb
===================================================================
--- graphviz-2.38.0.orig/config/config_ruby.rb
+++ graphviz-2.38.0/config/config_ruby.rb
@@ -4,8 +4,12 @@ CONFIG = RbConfig::MAKEFILE_CONFIG
 
 
 case ARGV[0]
+when "arch"
+    puts RbConfig::expand(CONFIG["arch"])
 when "archdir"
     puts RbConfig::expand(CONFIG["archdir"])
+when "hdrdir"
+    puts RbConfig::expand(CONFIG["rubyhdrdir"])
 when "lib"
     puts RbConfig::expand(CONFIG["libdir"])
 when "vendorarchdir"
Index: graphviz-2.38.0/configure.ac
===================================================================
--- graphviz-2.38.0.orig/configure.ac
+++ graphviz-2.38.0/configure.ac
@@ -1411,7 +1411,9 @@ else
           if test "x$RUBY" = "x"; then
 	    use_ruby="No (ruby not available)"
           else
-            RUBY_CFLAGS="-I`$RUBY $srcdir/config/config_ruby.rb archdir`"
+            rubyincdir=`$RUBY $srcdir/config/config_ruby.rb hdrdir`
+            rubyarch=`$RUBY $srcdir/config/config_ruby.rb arch`
+            RUBY_CFLAGS="-I$rubyincdir -I$rubyincdir/$rubyarch"
 	    # hack for powerpc-darwin8 (10.4)
 	    if test "x$DARWIN" = "xyes"; then
 	      RUBY_CFLAGS=`echo $RUBY_CFLAGS | sed 's/powerpc/universal/'`