diff --git a/doc/Gemfile.lock b/doc/Gemfile.lock
index adacad9..b4ac3f4 100644
--- a/doc/Gemfile.lock
+++ b/doc/Gemfile.lock
@@ -17,7 +17,7 @@ GEM
     coffee-script-source (1.12.2)
     compass-import-once (1.0.5)
       sass (>= 3.2, < 3.5)
-    concurrent-ruby (1.0.4)
+    concurrent-ruby (1.1.5)
     contracts (0.13.0)
     dotenv (2.2.0)
     erubis (2.7.0)
@@ -88,7 +88,7 @@ GEM
       activesupport (>= 3.1)
     parallel (1.10.0)
     public_suffix (2.0.5)
-    rack (2.0.1)
+    rack (2.0.7)
     rb-fsevent (0.9.8)
     rb-inotify (0.9.8)
       ffi (>= 0.5.0)
@@ -96,7 +96,7 @@ GEM
     rouge (2.0.7)
     sass (3.4.23)
     servolux (0.12.0)
-    sprockets (3.7.1)
+    sprockets (4.0.0)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     thor (0.19.4)