diff --git a/Gemfile b/Gemfile
index d8fc6f6..9acff00 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ end
 
 gem 'rails', '~> 5.2'
 gem 'pg', '>= 0.18', '< 2.0'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'rack-cors', require: 'rack/cors'
 gem 'bcrypt', '~> 3.1.7'
 gem 'knock', '1.4.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index fa4a758..a058f66 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -78,7 +78,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.8.2)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
@@ -92,7 +94,8 @@ GEM
       slop (~> 3.4)
     pry-rails (0.3.6)
       pry (>= 0.10.4)
-    puma (3.12.2)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-cors (1.0.5)
       rack (>= 1.6.0)
@@ -176,7 +179,7 @@ DEPENDENCIES
   listen (~> 3.0.5)
   pg (>= 0.18, < 2.0)
   pry-rails
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.2)
   rspec-rails (~> 3.8)