diff --git a/Gemfile b/Gemfile
index 8f8381e21..241149937 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,4 +2,4 @@ source 'https://rubygems.org'
 
 gem 'aruba', '~> 1.0.0.pre.alpha.4'
 gem 'cucumber', '~> 3.1.2'
-gem 'sinatra'
+gem 'sinatra', '>= 4.0.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 4b44e821b..bcdf07d19 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -9,6 +9,7 @@ GEM
       rspec-expectations (~> 3.4)
       thor (~> 0.19)
     backports (3.15.0)
+    base64 (0.2.0)
     builder (3.2.3)
     childprocess (1.0.1)
       rake (< 13.0)
@@ -35,22 +36,28 @@ GEM
     gherkin (5.1.0)
     multi_json (1.13.1)
     multi_test (0.1.2)
-    mustermann (1.0.3)
-    rack (2.0.7)
-    rack-protection (2.0.5)
-      rack
+    mustermann (3.0.0)
+      ruby2_keywords (~> 0.0.1)
+    rack (3.0.8)
+    rack-protection (4.0.0)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
     rake (12.3.3)
     rspec-expectations (3.8.4)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.8.0)
     rspec-support (3.8.2)
-    sinatra (2.0.5)
-      mustermann (~> 1.0)
-      rack (~> 2.0)
-      rack-protection (= 2.0.5)
+    ruby2_keywords (0.0.5)
+    sinatra (4.0.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.0.0)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
     thor (0.20.3)
-    tilt (2.0.9)
+    tilt (2.3.0)
 
 PLATFORMS
   java
@@ -59,7 +66,7 @@ PLATFORMS
 DEPENDENCIES
   aruba (~> 1.0.0.pre.alpha.4)
   cucumber (~> 3.1.2)
-  sinatra
+  sinatra (>= 4.0.0)
 
 BUNDLED WITH
-   1.17.1
+   1.17.3