diff --git a/Gemfile b/Gemfile
index a39062a0..99ebe500 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ gem 'rails', '4.2.8'
 # Use postgresql as the database for Active Record
 gem 'pg', '0.18.4'
 
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/Gemfile.lock b/Gemfile.lock
index b2ee38ec..8a39a82b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -148,6 +148,7 @@ GEM
     multi_xml (0.6.0)
     multipart-post (2.1.1)
     netrc (0.11.0)
+    nio4r (2.5.8)
     nokogiri (1.10.7)
       mini_portile2 (~> 2.4.0)
     orm_adapter (0.5.0)
@@ -155,7 +156,8 @@ GEM
     pry (0.12.2)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.12.2)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (1.6.12)
     rack-cors (1.0.6)
       rack (>= 1.6.0)
@@ -286,7 +288,7 @@ DEPENDENCIES
   jquery-rails
   pg (= 0.18.4)
   pry
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack-cors
   rails (= 4.2.8)
   rails_12factor