diff --git a/Gemfile b/Gemfile
index dc5c8ea..5c138d0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -16,7 +16,7 @@ gem "jquery-rails"
 gem "nested_form"
 gem "petergate"
 gem "pg", ">= 0.18", "< 2.0"
-gem "puma", "~> 3.11"
+gem "puma", "~> 4.3"
 gem "rails", "~> 5.2.3"
 gem "sass", "~> 3.7", ">= 3.7.4"
 gem "sass-rails", "~> 5.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index 8f8a833..7146940 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -123,7 +123,9 @@ 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)
@@ -144,7 +146,8 @@ GEM
       activerecord (> 4.0.0)
     pg (1.1.4)
     popper_js (1.14.5)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -302,7 +305,7 @@ DEPENDENCIES
   nested_form
   petergate
   pg (>= 0.18, < 2.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rails-controller-testing
   rspec-rails (~> 3.8)