diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index a91ae8b79f..f13a900634 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -935,4 +935,21 @@ class TestRegexp < Test::Unit::TestCase
     err = assert_raise(TypeError){ Regexp.quote(42) }
     assert_equal 'no implicit conversion of Fixnum into String', err.message, bug7539
   end
+
+  def test_conditional_expression
+    bug8583 = '[ruby-dev:47480] [Bug #8583]'
+
+    conds = {"xy"=>true, "yx"=>true, "xx"=>false, "yy"=>false}
+    assert_match_each(/\A((x)|(y))(?(2)y|x)\z/, conds, bug8583)
+    assert_match_each(/\A((?<x>x)|(?<y>y))(?(<x>)y|x)\z/, conds, bug8583)
+  end
+
+  def assert_match_each(re, conds, msg = nil)
+    errs = conds.select {|str, match| match ^ (re =~ str)}
+    msg = message(msg) {
+      "Expected #{re.inspect} to\n" +
+      errs.map {|str, match| "\t#{'not ' unless match}match #{str.inspect}"}.join(",\n")
+    }
+    assert(errs.empty?, msg)
+  end
 end