diff --git a/Gemfile b/Gemfile
index 69e4755..15c0f97 100644
--- a/Gemfile
+++ b/Gemfile
@@ -25,7 +25,7 @@ gem 'jquery-rails'
 gem 'twitter'
 
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+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 7cf9780..6e6909e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -160,7 +160,8 @@ GEM
       activerecord (>= 4.2)
       activesupport (>= 4.2)
     public_suffix (4.0.6)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     racc (1.6.0)
     rack (2.2.3)
     rack-test (1.1.0)
@@ -289,7 +290,7 @@ DEPENDENCIES
   omniauth-slack
   pg (~> 0.18)
   pg_search
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.3)
   sass-rails (~> 5.0)
   sassc-rails (~> 2.1.0)