diff --git a/Gemfile b/Gemfile
index aca39a6b..3bcafd1b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-gem 'sinatra', '~> 1.0'
+gem 'sinatra', '~> 4.1'
 gem 'shotgun', :group => :reloadable
 gem 'thin', :group => :reloadable
 gem 'rake'
diff --git a/Gemfile.lock b/Gemfile.lock
index 8ced3297..29fe2186 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,23 +1,37 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    base64 (0.3.0)
     daemons (1.1.9)
     eventmachine (1.0.4)
-    rack (1.6.0)
-    rack-protection (1.5.3)
-      rack
+    logger (1.7.0)
+    mustermann (3.0.4)
+      ruby2_keywords (~> 0.0.1)
+    rack (3.2.1)
+    rack-protection (4.1.0)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.1.1)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0)
     rake (10.4.2)
+    ruby2_keywords (0.0.5)
     shotgun (0.9)
       rack (>= 1.0)
-    sinatra (1.4.5)
-      rack (~> 1.4)
-      rack-protection (~> 1.4)
-      tilt (~> 1.3, >= 1.3.4)
-    thin (1.6.3)
+    sinatra (4.1.0)
+      logger (>= 1.6.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.1.0)
+      rack-session (>= 2.0.0, < 3)
+      tilt (~> 2.0)
+    thin (2.0.1)
       daemons (~> 1.0, >= 1.0.9)
-      eventmachine (~> 1.0)
-      rack (~> 1.0)
-    tilt (1.4.1)
+      eventmachine (~> 1.0, >= 1.0.4)
+      logger
+      rack (>= 1, < 4)
+    tilt (2.6.1)
 
 PLATFORMS
   ruby
@@ -25,5 +39,5 @@ PLATFORMS
 DEPENDENCIES
   rake
   shotgun
-  sinatra (~> 1.0)
+  sinatra (~> 4.1)
   thin