diff --git a/Gemfile b/Gemfile
index 333919d..b66e23d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.1'
 # Use sqlite3 as the database for Active Record
 gem 'pg'
 # 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 df7e8bc..e8299b4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -123,7 +123,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.9.2)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -165,7 +167,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -290,7 +293,7 @@ DEPENDENCIES
   omniauth-google-oauth2
   pg
   pry
-  puma (~> 3.7)
+  puma (~> 4.3)
   rack_session_access
   rails (~> 5.1)
   rspec-rails