diff --git a/Gemfile b/Gemfile
index 67d2bec..f1cc206 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@
 source 'https://rubygems.org'
 gem 'listen'
 gem 'pg'
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 4.3'
 gem 'rails', '~> 5.2.3'
 gem 'rubocop'
 gem 'settingslogic', '2.0.9'
diff --git a/Gemfile.lock b/Gemfile.lock
index 9599c75..d54864d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -66,7 +66,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.9.2)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
@@ -77,7 +79,8 @@ GEM
     parser (2.6.3.0)
       ast (~> 2.4.0)
     pg (1.1.4)
-    puma (3.12.1)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -142,7 +145,7 @@ PLATFORMS
 DEPENDENCIES
   listen
   pg
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rubocop
   settingslogic (= 2.0.9)