diff --git a/app/Gemfile b/app/Gemfile
index 4eae867..0f6a3dd 100644
--- a/app/Gemfile
+++ b/app/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.1.4'
 # Use sqlite3 as the database for Active Record
 gem 'pg', '~> 0.21.0'
 # 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/app/Gemfile.lock b/app/Gemfile.lock
index a00f229..96ab805 100644
--- a/app/Gemfile.lock
+++ b/app/Gemfile.lock
@@ -97,7 +97,8 @@ GEM
       mini_portile2 (~> 2.3.0)
     pg (0.21.0)
     public_suffix (3.0.1)
-    puma (3.11.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-cors (1.0.5)
       rack (>= 1.6.0)
@@ -200,7 +201,7 @@ DEPENDENCIES
   jwt
   listen (>= 3.0.5, < 3.2)
   pg (~> 0.21.0)
-  puma (~> 3.7)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.1.4)
   sass-rails (~> 5.0)