diff --git a/Gemfile b/Gemfile
index caedbdf..e414f05 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ gem 'rails', '~> 5.0.0', '>= 5.0.0.1'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 3.12', '>= 3.12.2'
 gem 'jquery-ui-rails'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 666a316..918dda5 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -82,7 +82,7 @@ GEM
     nio4r (1.2.1)
     nokogiri (1.6.8.1)
       mini_portile2 (~> 2.1.0)
-    puma (3.6.0)
+    puma (3.12.4)
     rack (2.0.1)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -162,7 +162,7 @@ DEPENDENCIES
   jquery-rails
   jquery-ui-rails
   listen (~> 3.0.5)
-  puma (~> 3.0)
+  puma (~> 3.12, >= 3.12.2)
   rails (~> 5.0.0, >= 5.0.0.1)
   sass-rails (~> 5.0)
   spring
@@ -174,4 +174,4 @@ DEPENDENCIES
   web-console
 
 BUNDLED WITH
-   1.12.5
+   1.17.3