diff --git a/Gemfile b/Gemfile
index 57f597292..b37a47d8d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -56,7 +56,7 @@ gem "rack-cors", "0.4.0", require: "rack/cors"
 gem "bootstrap-sass", "2.3.2.2"
 gem "compass-rails",  "2.0.5"
 gem "sass-rails",     "5.0.4"
-gem "autoprefixer-rails", "6.3.1"
+gem "autoprefixer-rails", "6.3.3.1"
 
 # Database
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 769331968..f23e60d8b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -57,9 +57,8 @@ GEM
     ast (2.2.0)
     astrolabe (1.3.1)
       parser (~> 2.2)
-    autoprefixer-rails (6.3.1)
+    autoprefixer-rails (6.3.3.1)
       execjs
-      json
     backbone-on-rails (1.2.0.0)
       eco
       ejs
@@ -115,7 +114,6 @@ GEM
       compass (~> 1.0.0)
       sass-rails (< 5.1)
       sprockets (< 2.13)
-    concurrent-ruby (1.0.1)
     configurate (0.3.1)
     connection_pool (2.2.0)
     crack (0.4.3)
@@ -786,7 +784,7 @@ DEPENDENCIES
   acts_as_api (= 0.4.2)
   addressable (= 2.3.8)
   asset_sync (= 1.1.0)
-  autoprefixer-rails (= 6.3.1)
+  autoprefixer-rails (= 6.3.3.1)
   backbone-on-rails (= 1.2.0.0)
   bootstrap-sass (= 2.3.2.2)
   capybara (= 2.6.2)