diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
index f3ccf95045b2e4ea9e3cb08e19cf01294e80ebde..511b4a82ebde24e653a42a8c10e2f46ab93b9411 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
@@ -18,7 +18,7 @@ Rails.application.configure do
 
     config.cache_store = :memory_store
     config.public_file_server.headers = {
-      'Cache-Control' => 'public, max-age=172800'
+      'Cache-Control' => "public, max-age=#{2.days.seconds.to_i}"
     }
   else
     config.action_controller.perform_caching = false
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
index 42fee3b0360636920afa8862a53c6e2e52a8f18a..56416b3075e42fee049760356e3a844a43c0b515 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
@@ -15,7 +15,7 @@ Rails.application.configure do
   # Configure public file server for tests with Cache-Control for performance.
   config.public_file_server.enabled = true
   config.public_file_server.headers = {
-    'Cache-Control' => 'public, max-age=3600'
+    'Cache-Control' => "public, max-age=#{1.hour.seconds.to_i}"
   }
 
   # Show full error reports and disable caching.