diff --git a/Gemfile.lock b/Gemfile.lock
index 614a3c1..aebc732 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -24,13 +24,14 @@ GEM
       autoprefixer-rails (>= 5.0.0.1)
       sass (>= 3.2.19)
     coderay (1.1.0)
+    concurrent-ruby (1.1.5)
     debug_inspector (0.0.2)
     diff-lcs (1.2.5)
     erubis (2.7.0)
     execjs (2.5.2)
     json (1.8.2)
     multi_json (1.11.0)
-    rack (1.6.0)
+    rack (1.6.11)
     rack-protection (1.5.3)
       rack
     rack-test (0.6.3)
@@ -63,8 +64,9 @@ GEM
       rack-test
       sinatra (~> 1.4.0)
       tilt (~> 1.3)
-    sprockets (3.0.1)
-      rack (~> 1.0)
+    sprockets (3.7.2)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
     tilt (1.4.1)
 
 PLATFORMS