diff --git a/app/models/oauth2_user_info.rb b/app/models/oauth2_user_info.rb
index ed9f217caa1..69f35ed731c 100644
--- a/app/models/oauth2_user_info.rb
+++ b/app/models/oauth2_user_info.rb
@@ -20,5 +20,6 @@ end
 #
 # Indexes
 #
-#  index_oauth2_user_infos_on_uid_and_provider  (uid,provider) UNIQUE
+#  index_oauth2_user_infos_on_uid_and_provider      (uid,provider) UNIQUE
+#  index_oauth2_user_infos_on_user_id_and_provider  (user_id,provider) UNIQUE
 #
diff --git a/db/migrate/20191022155215_add_index_to_oauth2_user_info.rb b/db/migrate/20191022155215_add_index_to_oauth2_user_info.rb
new file mode 100644
index 00000000000..dc9093a6c06
--- /dev/null
+++ b/db/migrate/20191022155215_add_index_to_oauth2_user_info.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddIndexToOauth2UserInfo < ActiveRecord::Migration[6.0]
+  def change
+    add_index :oauth2_user_infos, [:user_id, :provider], unique: true
+  end
+end