diff --git a/Gemfile b/Gemfile
index e3ddc13d8..daa313f79 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,6 +4,7 @@ gem "jekyll", "~> 4.3.2"
 
 # If you have any plugins, put them here!
 group :jekyll_plugins do
+  gem "jekyll-last-modified-at"
   gem "jekyll-redirect-from"
   gem "jekyll-sass-converter", github: 'jekyll/jekyll-sass-converter'
   gem "jekyll-sitemap"
diff --git a/Gemfile.lock b/Gemfile.lock
index 44618d8e8..0e148223f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -60,6 +60,9 @@ GEM
       safe_yaml (~> 1.0)
       terminal-table (>= 1.8, < 4.0)
       webrick (~> 1.7)
+    jekyll-last-modified-at (1.3.0)
+      jekyll (>= 3.7, < 5.0)
+      posix-spawn (~> 0.3.9)
     jekyll-redirect-from (0.16.0)
       jekyll (>= 3.3, < 5.0)
     jekyll-sitemap (1.4.0)
@@ -89,6 +92,7 @@ GEM
       hashery (~> 2.0)
       ruby-rc4
       ttfunk
+    posix-spawn (0.3.15)
     public_suffix (5.0.1)
     racc (1.6.2)
     rainbow (3.1.1)
@@ -123,6 +127,7 @@ PLATFORMS
 DEPENDENCIES
   html-proofer
   jekyll (~> 4.3.2)
+  jekyll-last-modified-at
   jekyll-redirect-from
   jekyll-sass-converter!
   jekyll-sitemap
diff --git a/_config.yml b/_config.yml
index 03bee9ea9..d85fc3d05 100644
--- a/_config.yml
+++ b/_config.yml
@@ -29,5 +29,6 @@ sass:
     - ../node_modules/*
 
 plugins:
+  - jekyll-last-modified-at
   - jekyll-redirect-from
   - jekyll-sitemap