diff --git a/ext/etc/extconf.rb b/ext/etc/extconf.rb
index 7c30b38bfd..1e8bd16d1d 100644
--- a/ext/etc/extconf.rb
+++ b/ext/etc/extconf.rb
@@ -43,9 +43,15 @@ have_struct_member('struct group', 'gr_passwd', 'grp.h')
 
 # for https://github.com/ruby/etc
 srcdir = File.expand_path("..", __FILE__)
-if !File.exist?("#{srcdir}/depend")
-  %x[#{RbConfig.ruby} #{srcdir}/mkconstants.rb -o #{srcdir}/constdefs.h]
+constdefs = "#{srcdir}/constdefs.h"
+ruby = RbConfig.ruby
+if File.file?(ruby)
+  ruby = [ruby]
+else
+  require "shellwords"
+  ruby = Shellwords.split(ruby)
 end
+system(*ruby, "#{srcdir}/mkconstants.rb", "-o", constdefs)
 
 # TODO: remove when dropping 2.7 support, as exported since 3.0
 have_func('rb_deprecate_constant(Qnil, "None")')