diff --git a/share/containers/rails/app/Gemfile b/share/containers/rails/app/Gemfile
index 56affb3..0c28b5a 100644
--- a/share/containers/rails/app/Gemfile
+++ b/share/containers/rails/app/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.2', '>= 5.2.2.1'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/share/containers/rails/app/Gemfile.lock b/share/containers/rails/app/Gemfile.lock
index 66f2fc8..30691b6 100644
--- a/share/containers/rails/app/Gemfile.lock
+++ b/share/containers/rails/app/Gemfile.lock
@@ -98,7 +98,9 @@ GEM
     marcel (0.3.2)
       mimemagic (~> 0.3.2)
     method_source (0.9.2)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     minitest (5.11.3)
     msgpack (1.1.0)
@@ -106,7 +108,8 @@ GEM
     nio4r (2.3.1)
     nokogiri (1.10.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-test (0.7.0)
       rack (>= 1.0, < 3)
@@ -201,7 +204,7 @@ DEPENDENCIES
   coffee-rails (~> 4.2)
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.2, >= 5.2.2.1)
   sass-rails (~> 5.0)
   selenium-webdriver