diff --git a/Gemfile b/Gemfile
index 3abfcbf..7260da8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,7 +2,7 @@ source 'https://rubygems.org'
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '5.0.0'
 # Use Puma as the app server
-gem 'puma', '3.4.0'
+gem 'puma', '3.12.6'
 # Use SCSS for stylesheets
 gem 'sass-rails', '5.0.6'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/Gemfile.lock b/Gemfile.lock
index aeb043e..1bd560f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -99,7 +99,9 @@ GEM
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.13.0)
@@ -116,7 +118,7 @@ GEM
       mimemagic (~> 0.3.0)
       terrapin (~> 0.6.0)
     pg (0.18.4)
-    puma (3.4.0)
+    puma (3.12.6)
     rack (2.0.6)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -223,7 +225,7 @@ DEPENDENCIES
   nokogiri (>= 1.8.2)
   paperclip (~> 6.0.0)
   pg (= 0.18.4)
-  puma (= 3.4.0)
+  puma (= 3.12.6)
   rack (>= 2.0.6)
   rails (= 5.0.0)
   rails-html-sanitizer (>= 1.0.4)