diff --git a/Gemfile b/Gemfile
index c2a937f5..8cbc0239 100644
--- a/Gemfile
+++ b/Gemfile
@@ -22,7 +22,7 @@ gem 'hootstrap', '~> 0.12.0'
 gem 'kaminari', '~> 1.1'
 gem 'local_time', '~> 2.1'
 gem 'pg', '~> 1.1'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'rack-cors', '~> 1.0'
 gem 'rails', '~> 5.2.3'
 gem 'sass-rails', '~> 5.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 7e42701d..e1660ed3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -177,7 +177,9 @@ GEM
       mimemagic (~> 0.3.2)
     metaclass (0.0.4)
     method_source (0.9.2)
-    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)
@@ -207,7 +209,8 @@ GEM
     pg (1.1.4)
     popper_js (1.14.5)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-cors (1.0.3)
     rack-proxy (0.6.4)
@@ -339,7 +342,7 @@ DEPENDENCIES
   minitest-rails-capybara
   mocha (~> 1.8)
   pg (~> 1.1)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack-cors (~> 1.0)
   rails (~> 5.2.3)
   ruby-progressbar (~> 1.10)