diff --git a/Gemfile b/Gemfile
index 47807700..6aebe20d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ else
   gem "rails_test_params_backport", group: :test
 end
 
-gem 'pg'
+gem 'pg', '~> 0.21'
 gem 'sqlite3'
 gem 'mysql2'