diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 2bf4649f14..b4e4f725b3 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -1396,6 +1396,15 @@ class TestRegexp < Test::Unit::TestCase
     end
   end
 
+  def test_invalid_group
+    assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
+    begin;
+      assert_raise_with_message(RegexpError, /invalid conditional pattern/) do
+        Regexp.new("((?(1)x|x|)x)+")
+      end
+    end;
+  end
+
   # This assertion is for porting x2() tests in testpy.py of Onigmo.
   def assert_match_at(re, str, positions, msg = nil)
     re = Regexp.new(re) unless re.is_a?(Regexp)
diff --git a/version.h b/version.h
index ca369e8d47..9a9913c2c1 100644
--- a/version.h
+++ b/version.h
@@ -11,11 +11,11 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 2
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 20
+#define RUBY_PATCHLEVEL 21
 
 #define RUBY_RELEASE_YEAR 2022
-#define RUBY_RELEASE_MONTH 4
-#define RUBY_RELEASE_DAY 16
+#define RUBY_RELEASE_MONTH 5
+#define RUBY_RELEASE_DAY 1
 
 #include "ruby/version.h"