diff --git a/common.mk b/common.mk
index c8434b9b7b..1f33a9a3ac 100644
--- a/common.mk
+++ b/common.mk
@@ -1666,36 +1666,37 @@ help: PHONY
 	"                Makefile of Ruby" \
 	"" \
 	"targets:" \
-	"  all (default):       builds all of below" \
-	"  miniruby:            builds only miniruby" \
-	"  encs:                builds encodings" \
-	"  exts:                builds extensions" \
-	"  main:                builds encodings, extensions and ruby" \
-	"  docs:                builds documents" \
-	"  install-capi:        builds C API documents" \
-	"  run:                 runs test.rb by miniruby" \
-	"  runruby:             runs test.rb by ruby you just built" \
-	"  gdb:                 runs test.rb by miniruby under gdb" \
-	"  gdb-ruby:            runs test.rb by ruby under gdb" \
-	"  check:               equals make test test-tool test-all test-spec" \
-	"  test:                ruby core tests [BTESTS=<bootstraptest files>]" \
-	"  test-all:            all ruby tests [TESTOPTS=-j4 TESTS=<test files>]" \
-	"  test-spec:           run the Ruby spec suite [SPECOPTS=<specs, opts>]" \
-	"  test-bundler:        run the Bundler spec" \
-	"  test-bundled-gems:   run the test suite of bundled gems" \
-	"  test-tool:           tests under the tool/test" \
-	"  update-gems:         download files of the bundled gems" \
-	"  update-bundled_gems: update the latest version of bundled gems" \
-	"  sync-default-gems:   sync default gems from upstream [GEM=<gem_name git_ref>]" \
-	"  up:                  update local copy and autogenerated files" \
-	"  benchmark:           benchmark this ruby and COMPARE_RUBY." \
-	"  gcbench:             gc benchmark [GCBENCH_ITEM=<item_name>]" \
-	"  install:             install all ruby distributions" \
-	"  install-nodoc:       install without rdoc" \
-	"  install-cross:       install cross compiling stuff" \
-	"  clean:               clean for tarball" \
-	"  distclean:           clean for repository" \
-	"  golf:                build goruby for golfers" \
+	"  all (default):         builds all of below" \
+	"  miniruby:              builds only miniruby" \
+	"  encs:                  builds encodings" \
+	"  exts:                  builds extensions" \
+	"  main:                  builds encodings, extensions and ruby" \
+	"  docs:                  builds documents" \
+	"  install-capi:          builds C API documents" \
+	"  run:                   runs test.rb by miniruby" \
+	"  runruby:               runs test.rb by ruby you just built" \
+	"  gdb:                   runs test.rb by miniruby under gdb" \
+	"  gdb-ruby:              runs test.rb by ruby under gdb" \
+	"  check:                 equals make test test-tool test-all test-spec" \
+	"  test:                  ruby core tests [BTESTS=<bootstraptest files>]" \
+	"  test-all:              all ruby tests [TESTOPTS=-j4 TESTS=<test files>]" \
+	"  test-spec:             run the Ruby spec suite [SPECOPTS=<specs, opts>]" \
+	"  test-bundler:          run the Bundler spec" \
+	"  test-bundler-parallel: run the Bundler spec with parallel" \
+	"  test-bundled-gems:     run the test suite of bundled gems" \
+	"  test-tool:             tests under the tool/test" \
+	"  update-gems:           download files of the bundled gems" \
+	"  update-bundled_gems:   update the latest version of bundled gems" \
+	"  sync-default-gems:     sync default gems from upstream [GEM=<gem_name git_ref>]" \
+	"  up:                    update local copy and autogenerated files" \
+	"  benchmark:             benchmark this ruby and COMPARE_RUBY." \
+	"  gcbench:               gc benchmark [GCBENCH_ITEM=<item_name>]" \
+	"  install:               install all ruby distributions" \
+	"  install-nodoc:         install without rdoc" \
+	"  install-cross:         install cross compiling stuff" \
+	"  clean:                 clean for tarball" \
+	"  distclean:             clean for repository" \
+	"  golf:                  build goruby for golfers" \
 	$(HELP_EXTRA_TASKS) \
 	"see DeveloperHowto for more detail: " \
 	"  https://bugs.ruby-lang.org/projects/ruby/wiki/DeveloperHowto" \