diff --git a/Gemfile.lock b/Gemfile.lock
index 8cdac9e..244e960 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -12,11 +12,11 @@ GEM
     crack (0.4.4)
     diff-lcs (1.3)
     hashdiff (1.0.1)
-    mustermann (1.1.1)
+    mustermann (3.0.0)
       ruby2_keywords (~> 0.0.1)
     public_suffix (4.0.6)
-    rack (2.2.3)
-    rack-protection (2.1.0)
+    rack (2.2.4)
+    rack-protection (3.0.4)
       rack
     rspec (3.9.0)
       rspec-core (~> 3.9.0)
@@ -31,13 +31,13 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.9.0)
     rspec-support (3.9.2)
-    ruby2_keywords (0.0.2)
-    sinatra (2.1.0)
-      mustermann (~> 1.0)
-      rack (~> 2.2)
-      rack-protection (= 2.1.0)
+    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)
-    tilt (2.0.10)
+    tilt (2.0.11)
     webmock (3.10.0)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
@@ -51,7 +51,7 @@ DEPENDENCIES
   byebug (~> 11.1.3)
   circuit-api!
   rspec (~> 3.1)
-  sinatra (~> 2.1.0)
+  sinatra (~> 3.0.4)
   webmock (~> 3.10.0)
 
 BUNDLED WITH
diff --git a/circuit-rest-client.gemspec b/circuit-rest-client.gemspec
index 99c1c93..7921e23 100644
--- a/circuit-rest-client.gemspec
+++ b/circuit-rest-client.gemspec
@@ -20,5 +20,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rspec', '~> 3.1'
   s.add_development_dependency 'byebug', '~> 11.1.3'
   s.add_development_dependency 'webmock', '~> 3.10.0'
-  s.add_development_dependency 'sinatra', '~> 2.1.0'
+  s.add_development_dependency 'sinatra', '~> 3.0.4'
 end