diff --git a/Gemfile.lock b/Gemfile.lock
index 2961002..afef0a0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,16 +1,18 @@
 GIT
-  remote: git://github.com/rails/sprockets.git
-  revision: 44a829ea5def98acbbc2dab70f5d77459b7555d0
+  remote: https://github.com/rails/sprockets.git
+  revision: 0f3e0e93dabafa8f3027e8036e40fd08902688c8
   specs:
-    sprockets (4.0.0)
-      rack (~> 1.0)
+    sprockets (4.0.3)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
 
 GEM
   remote: https://rubygems.org/
   specs:
+    concurrent-ruby (1.1.10)
     execjs (2.5.2)
     json (1.8.3)
-    rack (1.6.12)
+    rack (2.1.4.1)
     sass (3.4.16)
     uglifier (2.7.1)
       execjs (>= 0.3.0)