diff --git a/Gemfile b/Gemfile
index bea9f5d..cffbb0e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.0.6'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 0.18'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 3.12', '>= 3.12.4'
 gem 'bootstrap-sass', '~> 3.3.6'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 4446152..62a0ee7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -89,7 +89,7 @@ GEM
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     pg (0.21.0)
-    puma (3.10.0)
+    puma (3.12.4)
     rack (2.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -173,7 +173,7 @@ DEPENDENCIES
   jquery-rails
   listen (~> 3.0.5)
   pg (~> 0.18)
-  puma (~> 3.0)
+  puma (~> 3.12, >= 3.12.4)
   rails (~> 5.0.6)
   sass-rails (~> 5.0)
   spring
@@ -184,4 +184,4 @@ DEPENDENCIES
   web-console (>= 3.3.0)
 
 BUNDLED WITH
-   1.10.6
+   1.17.3