diff --git a/Gemfile b/Gemfile
index d5811ab..a7e824e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,7 +13,7 @@ gem 'tiny_tds'
 gem 'activerecord-sqlserver-adapter'
 
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 4.3'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.5'
 # Use Redis adapter to run Action Cable in production
diff --git a/Gemfile.lock b/Gemfile.lock
index f68db3a..64e5f91 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -117,7 +117,9 @@ GEM
     mime-types (3.3)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2019.1009)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.12.2)
@@ -140,8 +142,10 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
       spoon (~> 0.0)
-    puma (3.12.1)
-    puma (3.12.1-java)
+    puma (4.3.11)
+      nio4r (~> 2.0)
+    puma (4.3.11-java)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-protection (2.0.7)
       rack
@@ -272,7 +276,7 @@ DEPENDENCIES
   hsds_transformer (= 0.0.5)
   listen (>= 3.0.5, < 3.2)
   pry
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.2)
   rspec-rails
   spring