diff --git a/Gemfile.lock b/Gemfile.lock
index a74c81e..328108c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -24,7 +24,7 @@ GEM
     coffee-script-source (1.12.2)
     compass-import-once (1.0.5)
       sass (>= 3.2, < 3.5)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.5)
     contracts (0.13.0)
     dotenv (2.2.0)
     em-websocket (0.5.1)
@@ -115,7 +115,7 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     public_suffix (2.0.5)
-    rack (2.0.1)
+    rack (2.1.2)
     rack-livereload (0.3.16)
       rack
     rake (12.0.0)
@@ -127,7 +127,7 @@ GEM
     sass (3.4.23)
     servolux (0.12.0)
     slop (3.6.0)
-    sprockets (3.7.1)
+    sprockets (4.0.0)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     thor (0.19.4)