diff --git a/Gemfile.lock b/Gemfile.lock
index cd22fde6..8dd569d0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -202,9 +202,9 @@ GEM
     sassc-embedded (1.69.1)
       sass-embedded (~> 1.69)
     servolux (0.13.0)
-    sprockets (3.7.2)
+    sprockets (4.2.1)
       concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
+      rack (>= 2.2.4, < 4)
     temple (0.10.3)
     thor (1.3.0)
     tilt (2.0.11)