diff --git a/Gemfile b/Gemfile
index a6e7708..285c111 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ ruby '2.4.1'
 gem 'foreman'
 
 # Web framework
-gem 'sinatra', '~> 2.0.2'
+gem 'sinatra', '~> 2.2.3'
 
 # SSL enforcer
 gem 'rack-ssl-enforcer'
diff --git a/Gemfile.lock b/Gemfile.lock
index d18aa4d..e02590a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -61,7 +61,8 @@ GEM
     mini_mime (1.0.0)
     mini_portile2 (2.4.0)
     multi_json (1.13.1)
-    mustermann (1.0.3)
+    mustermann (2.0.2)
+      ruby2_keywords (~> 0.0.1)
     nenv (0.3.0)
     nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
@@ -75,8 +76,8 @@ GEM
       pry (~> 0.9)
       slop (~> 3.0)
     public_suffix (3.0.2)
-    rack (2.2.2)
-    rack-protection (2.0.3)
+    rack (2.2.4)
+    rack-protection (2.2.3)
       rack
     rack-ssl-enforcer (0.2.9)
     rack-test (1.0.0)
@@ -102,6 +103,7 @@ GEM
     rspec-support (3.7.1)
     ruby-enum (0.7.2)
       i18n
+    ruby2_keywords (0.0.5)
     ruby_dep (1.5.0)
     shellany (0.0.1)
     simplecov (0.16.1)
@@ -109,10 +111,10 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    sinatra (2.0.3)
-      mustermann (~> 1.0)
-      rack (~> 2.0)
-      rack-protection (= 2.0.3)
+    sinatra (2.2.3)
+      mustermann (~> 2.0)
+      rack (~> 2.2)
+      rack-protection (= 2.2.3)
       tilt (~> 2.0)
     slim (3.0.9)
       temple (>= 0.7.6, < 0.9)
@@ -120,7 +122,7 @@ GEM
     slop (3.6.0)
     temple (0.8.0)
     thor (0.19.4)
-    tilt (2.0.8)
+    tilt (2.0.11)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.5)
@@ -146,7 +148,7 @@ DEPENDENCIES
   rerun
   rspec
   simplecov
-  sinatra (~> 2.0.2)
+  sinatra (~> 2.2.3)
   slim
 
 RUBY VERSION