diff --git a/Gemfile b/Gemfile
index 08170e30..7f25aa46 100644
--- a/Gemfile
+++ b/Gemfile
@@ -83,6 +83,8 @@ gem 'jquery-ui-rails', '~> 4.2.1'
 # for languages validation
 gem 'iso-639'
 
+gem 'thor', '0.19.1'
+
 # frontend javascripts
 source 'https://rails-assets.org' do
   # for placeholder images
diff --git a/Gemfile.lock b/Gemfile.lock
index faaa8246..d6d8eb3b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -511,7 +511,7 @@ GEM
     sysexits (1.2.0)
     term-ansicolor (1.3.2)
       tins (~> 1.0)
-    thor (0.19.4)
+    thor (0.19.1)
     thread_safe (0.3.6)
     tilt (1.4.1)
     timecop (0.7.1)
@@ -651,6 +651,7 @@ DEPENDENCIES
   sqlite3
   stripe
   stripe-ruby-mock
+  thor (= 0.19.1)
   timecop
   transitions
   turbolinks