diff --git a/Gemfile b/Gemfile
index 18fc1b69c4aad577da9fadf0e643051da89e324c..6a017c3fbbc05a3870392bd8b0aa0aa17bf3a2f2 100644
--- a/Gemfile
+++ b/Gemfile
@@ -31,7 +31,7 @@ gem 'simple_captcha2', '0.3.2', :require => 'simple_captcha'
 # Background processing
 
 gem 'sidekiq', '3.3.0'
-gem 'sinatra', '1.3.3'
+gem 'sinatra', '1.4.5'
 
 # Scheduled processing
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 0ba7158c8d2e287c645fd0c17c4d1207a66dc611..3b6b785ee34037b023f89bbbc6db769028577406 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -531,10 +531,10 @@ GEM
     simple_captcha2 (0.3.2)
       rails (>= 4.1)
     simple_oauth (0.2.0)
-    sinatra (1.3.3)
-      rack (~> 1.3, >= 1.3.6)
-      rack-protection (~> 1.2)
-      tilt (~> 1.3, >= 1.3.3)
+    sinatra (1.4.5)
+      rack (~> 1.4)
+      rack-protection (~> 1.4)
+      tilt (~> 1.3, >= 1.3.4)
     sinon-rails (1.10.3)
       railties (>= 3.1)
     slop (3.6.0)
@@ -686,7 +686,7 @@ DEPENDENCIES
   sidekiq (= 3.3.0)
   sidetiq (= 0.6.3)
   simple_captcha2 (= 0.3.2)
-  sinatra (= 1.3.3)
+  sinatra (= 1.4.5)
   sinon-rails (= 1.10.3)
   spork (= 1.0.0rc4)
   test_after_commit (= 0.4.0)