diff --git a/ext/io/console/extconf.rb b/ext/io/console/extconf.rb
index 79f5838c5e..2f363152e3 100644
--- a/ext/io/console/extconf.rb
+++ b/ext/io/console/extconf.rb
@@ -13,7 +13,7 @@ else
   ok = false
 end
 ok &&= enable_config("io-console-force-compatible-with-1.8") ||
-  macro_defined?("HAVE_RUBY_IO_H", "ruby.h")
+  macro_defined?("HAVE_RUBY_IO_H", cpp_include("ruby.h"))
 if ok
   have_header("sys/ioctl.h")
   have_func("rb_check_hash_type", "ruby.h")