diff --git a/Gemfile b/Gemfile
index 3678646..8f0fa47 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ ruby '2.5.1'
 
 gem 'rails', '~> 5.2.0'
 gem 'pg', '>= 0.18', '< 2.0'
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 gem 'bootsnap', '>= 1.1.0', require: false
 gem 'graphql'
 gem 'graphiql-rails'
diff --git a/Gemfile.lock b/Gemfile.lock
index dc76d25..ca564a0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -119,7 +119,9 @@ GEM
     marcel (0.3.2)
       mimemagic (~> 0.3.2)
     method_source (0.9.0)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.0)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -129,7 +131,8 @@ GEM
       mini_portile2 (~> 2.3.0)
     pg (1.0.0)
     public_suffix (3.0.2)
-    puma (3.12.0)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-test (1.0.0)
       rack (>= 1.0, < 3)
@@ -196,7 +199,7 @@ DEPENDENCIES
   letter_opener
   listen (>= 3.0.5, < 3.2)
   pg (>= 0.18, < 2.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.0)
   spring
   spring-watcher-listen (~> 2.0.0)