diff --git a/Gemfile b/Gemfile
index b513739..28a9453 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,7 +2,7 @@
 
 source 'https://rubygems.org'
 
-gem 'sinatra', '~> 2.0.8'
+gem 'sinatra', '~> 3.0.4'
 gem 'sinatra-contrib'
 
 group :development do
diff --git a/Gemfile.lock b/Gemfile.lock
index a28b60b..8c38e2a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,16 +2,15 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.0)
-    backports (3.17.0)
     jaro_winkler (1.5.4)
-    multi_json (1.14.1)
-    mustermann (1.1.1)
+    multi_json (1.15.0)
+    mustermann (3.0.0)
       ruby2_keywords (~> 0.0.1)
     parallel (1.19.1)
     parser (2.7.0.5)
       ast (~> 2.4.0)
-    rack (2.2.2)
-    rack-protection (2.0.8.1)
+    rack (2.2.4)
+    rack-protection (3.0.4)
       rack
     rainbow (3.0.0)
     rexml (3.2.4)
@@ -24,20 +23,19 @@ GEM
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 1.7)
     ruby-progressbar (1.10.1)
-    ruby2_keywords (0.0.2)
-    sinatra (2.0.8.1)
-      mustermann (~> 1.0)
-      rack (~> 2.0)
-      rack-protection (= 2.0.8.1)
+    ruby2_keywords (0.0.5)
+    sinatra (3.0.4)
+      mustermann (~> 3.0)
+      rack (~> 2.2, >= 2.2.4)
+      rack-protection (= 3.0.4)
       tilt (~> 2.0)
-    sinatra-contrib (2.0.8.1)
-      backports (>= 2.8.2)
+    sinatra-contrib (3.0.4)
       multi_json
-      mustermann (~> 1.0)
-      rack-protection (= 2.0.8.1)
-      sinatra (= 2.0.8.1)
+      mustermann (~> 3.0)
+      rack-protection (= 3.0.4)
+      sinatra (= 3.0.4)
       tilt (~> 2.0)
-    tilt (2.0.10)
+    tilt (2.0.11)
     unicode-display_width (1.6.1)
 
 PLATFORMS
@@ -45,7 +43,7 @@ PLATFORMS
 
 DEPENDENCIES
   rubocop
-  sinatra (~> 2.0.8)
+  sinatra (~> 3.0.4)
   sinatra-contrib
 
 BUNDLED WITH