diff --git a/Gemfile b/Gemfile
index 278c7b1..b58b83b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -78,7 +78,7 @@ end
 group :production do
   gem 'pg'
   gem 'rails_12factor'
-  gem 'puma', '= 3.10.0'
+  gem 'puma', '4.3.5'
   gem 'clockwork'
 end
 
diff --git a/Gemfile.lock b/Gemfile.lock
index f0e40fb..8b17730 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -62,7 +62,7 @@ GEM
     annotate (2.6.5)
       activerecord (>= 2.3.0)
       rake (>= 0.8.7)
-    arbre (1.0.2)
+    arbre (1.1.1)
       activesupport (>= 3.0.0)
     arel (6.0.4)
     ast (2.3.0)
@@ -148,7 +148,8 @@ GEM
       actionpack (>= 4.1, < 5.2)
       activesupport (>= 4.1, < 5.2)
     hashie (3.5.6)
-    i18n (0.8.6)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
     inherited_resources (1.7.2)
       actionpack (>= 3.2, < 5.2.x)
       has_scope (~> 0.6)
@@ -197,6 +198,7 @@ GEM
     multi_json (1.12.2)
     multi_xml (0.6.0)
     multipart-post (2.0.0)
+    nio4r (2.3.1)
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     oauth (0.5.3)
@@ -239,7 +241,8 @@ GEM
     pry (0.11.1)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.10.0)
+    puma (4.3.5)
+      nio4r (~> 2.0)
     rack (1.6.8)
     rack-mini-profiler (0.10.5)
       rack (>= 1.2.0)
@@ -364,7 +367,7 @@ GEM
     thor (0.20.0)
     thread_safe (0.3.6)
     tilt (2.0.8)
-    tzinfo (1.2.3)
+    tzinfo (1.2.7)
       thread_safe (~> 0.1)
     uglifier (3.2.0)
       execjs (>= 0.3.0, < 3)
@@ -411,7 +414,7 @@ DEPENDENCIES
   paperclip
   pg
   pry
-  puma (= 3.10.0)
+  puma (= 4.3.5)
   rack-mini-profiler
   rails
   rails_12factor