diff --git a/Gemfile b/Gemfile
index e5cae14..685651b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -29,7 +29,7 @@ gem 'sass-rails', '5.0.7'
 # bundle exec rake doc:rails generates the API under doc/api.
 gem 'sdoc', '~> 1.0.0', group: :doc
 gem 'turbolinks', '5.2.1'
-gem 'uglifier', '4.1.7' # lock at 4.1.7
+gem 'uglifier', '4.2.0' # lock at 4.1.7
 gem 'wicked_pdf', '~> 1.4.0'
 gem 'wkhtmltopdf-binary', '~>0.12.4'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 5e9bcd7..bee754b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -311,7 +311,7 @@ GEM
     turbolinks-source (5.2.0)
     tzinfo (1.2.6)
       thread_safe (~> 0.1)
-    uglifier (4.1.7)
+    uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext
@@ -371,7 +371,7 @@ DEPENDENCIES
   spring (~> 2.0.2)
   sqlite3 (~> 1.3.13)
   turbolinks (= 5.2.1)
-  uglifier (= 4.1.7)
+  uglifier (= 4.2.0)
   wicked_pdf (~> 1.4.0)
   wkhtmltopdf-binary (~> 0.12.4)