diff --git a/Gemfile b/Gemfile
index ec1e853..fdb6596 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ gem 'haml'
 gem 'jbuilder', '~> 2.5'
 gem 'mongoid'
 gem 'pry'
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 gem 'rails', '~> 5.2.3'
 gem 'rubocop'
 gem 'sass-rails', '~> 5.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 9c1e9a7..930b61f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -103,7 +103,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.9.2)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.12.2)
@@ -123,7 +125,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -229,7 +232,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   mongoid
   pry
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rubocop
   sass-rails (~> 5.0)