diff --git a/webapp/Gemfile b/webapp/Gemfile
index 0c332d0..881d584 100644
--- a/webapp/Gemfile
+++ b/webapp/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.2'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3', '~> 1.3.6'
 # 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/webapp/Gemfile.lock b/webapp/Gemfile.lock
index 32f5e11..d05c2b6 100644
--- a/webapp/Gemfile.lock
+++ b/webapp/Gemfile.lock
@@ -113,7 +113,8 @@ GEM
     nokogiri (1.10.1)
       mini_portile2 (~> 2.4.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -209,7 +210,7 @@ DEPENDENCIES
   jquery-rails
   jquery-ui-rails
   listen (>= 3.0.5, < 3.2)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.2)
   sass-rails (~> 5.0)
   selenium-webdriver