diff --git a/Gemfile b/Gemfile
index f4756de..3f4a418 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 gem 'fastreader'
 gem 'nokogiri'
-gem 'rack', '~> 1.1'
+gem 'rack', '~> 3.0', '>= 3.0.0'
 gem 'rspec'
 gem 'pdfkit', '~> 0.5'
diff --git a/Gemfile.lock b/Gemfile.lock
index 1702514..3b8b9e2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -37,7 +37,7 @@ GEM
     nokogiri (1.6.8.1)
       mini_portile2 (~> 2.1.0)
     pdfkit (0.5.2)
-    rack (1.6.4)
+    rack (3.0.0)
     rake (11.3.0)
     rspec (3.5.0)
       rspec-core (~> 3.5.0)
@@ -66,9 +66,9 @@ PLATFORMS
 DEPENDENCIES
   fastreader
   nokogiri
-  pdfkit (= 0.5.2)
-  rack (~> 1.1)
+  pdfkit (~> 0.5)
+  rack (~> 3.0, >= 3.0.0)
   rspec
 
 BUNDLED WITH
-   1.13.6
+   1.17.3