diff --git a/Gemfile b/Gemfile
index 22520c65..5555593d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,6 +8,7 @@ gemspec
 group :development do
   gem "rake"
   gem "rdoc"
+  gem 'rbs', '4.1.0.pre.2' if RUBY_ENGINE == 'jruby' # FIXME: https://github.com/ruby/rdoc/issues/1746
 end
 
 group :benchmark do