diff --git a/app/controllers/user_avatars_controller.rb b/app/controllers/user_avatars_controller.rb
index cf8640e27d8..e5ec3087969 100644
--- a/app/controllers/user_avatars_controller.rb
+++ b/app/controllers/user_avatars_controller.rb
@@ -29,6 +29,7 @@ class UserAvatarsController < ApplicationController
     end
 
     image = LetterAvatar.generate(params[:username].to_s, params[:size].to_i)
+    response.headers["Last-Modified"] = File.ctime(image).httpdate
     expires_in 1.year, public: true
     send_file image, disposition: nil
   end
diff --git a/lib/letter_avatar.rb b/lib/letter_avatar.rb
index 61c80c87e82..d7da8541e57 100644
--- a/lib/letter_avatar.rb
+++ b/lib/letter_avatar.rb
@@ -25,7 +25,7 @@ class LetterAvatar
 
 
     def cache_path
-      "tmp/letter_avatars/#{VERSION}"
+      "public/uploads/letter_avatars/#{VERSION}"
     end
 
     def generate(username, size, opts = nil)