diff --git a/pre_commit/languages/ruby.py b/pre_commit/languages/ruby.py
index 18f304e5..7b018c1a 100644
--- a/pre_commit/languages/ruby.py
+++ b/pre_commit/languages/ruby.py
@@ -88,7 +88,8 @@ def install_environment(repo_cmd_runner, version='default'):
             if version != 'default':
                 _install_ruby(ruby_env, version)
             ruby_env.run(
-                'cd {prefix} && gem build *.gemspec && gem install *.gem',
+                'cd {prefix} && gem build *.gemspec'
+                ' && gem install --no-document *.gem',
             )