diff --git a/Gemfile b/Gemfile
index db3b9b0..3dab8f9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,7 +20,7 @@ gem "flipper-active_record", "~> 0.16"
 gem "flipper-ui", "~> 0.16"
 gem "mailgun-ruby", "~> 1.1"
 gem "pg", "~> 1.1.0"
-gem "puma", "~> 3.12"
+gem "puma", "~> 4.3"
 gem "uglifier", "~> 4.1"
 gem "webpacker", "~> 3.5"
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 3f0d951..07333be 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -190,7 +190,9 @@ GEM
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2019.0331)
-    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)
@@ -210,7 +212,8 @@ GEM
       byebug (~> 11.0)
       pry (~> 0.10)
     public_suffix (3.0.3)
-    puma (3.12.2)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-protection (2.0.5)
       rack
@@ -380,7 +383,7 @@ DEPENDENCIES
   mailgun-ruby (~> 1.1)
   pg (~> 1.1.0)
   pry-byebug
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.1)
   rails-erd
   rspec-rails