diff --git a/Gemfile b/Gemfile
index 76f33d2..b0d580d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ gem "sqlite3"
 # We will use pg later on to replace sqlite
 gem "pg"
 # Use Puma as the app server
-gem "puma", "~> 3.11"
+gem "puma", "~> 4.3"
 # Use SCSS for stylesheets
 gem "sass-rails", "~> 5.0"
 # Use Uglifier as compressor for JavaScript assets
diff --git a/Gemfile.lock b/Gemfile.lock
index 000952d..0058444 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -82,7 +82,9 @@ 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 (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
@@ -95,7 +97,8 @@ GEM
       ast (~> 2.4.0)
     pg (1.1.4)
     popper_js (1.14.5)
-    puma (3.12.1)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -223,7 +226,7 @@ DEPENDENCIES
   jquery-rails
   listen (>= 3.0.5, < 3.2)
   pg
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rspec-rails
   sass-rails (~> 5.0)