diff --git a/Gemfile b/Gemfile
index 7025f29d..92195457 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,7 +14,7 @@ gem 'rails', '~> 5.2.1'
 # Use sqlite3 and postgres as the database for Active Record
 gem 'sqlite3', '~> 1.3.6' # development and testing
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets, integrate C implementation of Sass, LibSass, into asset pipeline
 gem 'sassc-rails' # https://github.com/sass/sassc-rails
 # Use Uglifier as compressor for JavaScript assets
diff --git a/Gemfile.lock b/Gemfile.lock
index b0e4f0dd..29d5118d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -180,7 +180,9 @@ GEM
       rack-contrib (>= 1.1, < 3)
       railties (>= 3.0.0, < 6)
     method_source (0.9.2)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mina (1.2.3)
       open4 (~> 1.3.4)
       rake
@@ -232,7 +234,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     pundit (2.0.1)
       activesupport (>= 3.0.0)
     rack (2.0.6)
@@ -429,7 +432,7 @@ DEPENDENCIES
   omniauth
   omniauth_openid_connect
   pg
-  puma (~> 3.11)
+  puma (~> 4.3)
   pundit
   rails (~> 5.2.1)
   rails-controller-testing