diff --git a/Gemfile.lock b/Gemfile.lock
index f4dfa11..16d45da 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -45,6 +45,7 @@ GEM
       coffee-script-source
       execjs
     coffee-script-source (1.9.1.1)
+    concurrent-ruby (1.1.5)
     erubis (2.7.0)
     execjs (2.5.2)
     globalid (0.3.5)
@@ -67,7 +68,7 @@ GEM
     pg (0.18.2)
     prizm (0.0.3)
       rmagick
-    rack (1.6.1)
+    rack (1.6.11)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (4.2.1)
@@ -108,8 +109,9 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (~> 1.1)
-    sprockets (3.1.0)
-      rack (~> 1.0)
+    sprockets (3.7.2)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
     sprockets-rails (2.3.1)
       actionpack (>= 3.0)
       activesupport (>= 3.0)