diff --git a/Gemfile b/Gemfile
index e66c796..d4dcd41 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,7 +13,7 @@ gem 'graphql'
 gem 'graphql-batch'
 gem 'jwt'
 gem 'pg'
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 gem 'rack-cors'
 gem 'rails', '~> 5.2.3'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 69e3f78..e397430 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -127,7 +127,9 @@ 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 (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
@@ -146,7 +148,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.1.0)
-    puma (3.12.1)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-cors (1.0.3)
     rack-test (1.1.0)
@@ -256,7 +259,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pg
   pry
-  puma (~> 3.11)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.2.3)
   rspec-rails