diff --git a/Gemfile b/Gemfile
index 9e891a886..aacd8eb5f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -92,7 +92,6 @@ gem "sassc-rails", "~> 2.1.2" # Integrate SassC-Ruby into Rails
 gem "sidekiq", "~> 6.1.2" # Sidekiq is used to process background jobs with the help of Redis
 gem "sidekiq-cron", "~> 1.1" # Allows execution of scheduled cron jobs as specific times
 gem "sidekiq-unique-jobs", "~> 6.0.25" # Ensures that Sidekiq jobs are unique when enqueued
-gem "simpleidn", "~> 0.1" # Convert IDN domains to Punycode
 gem "sitemap_generator", "~> 6.1" # SitemapGenerator is a framework-agnostic XML Sitemap generator
 gem "slack-notifier", "~> 2.3" # A slim ruby wrapper for posting to slack webhooks
 gem "sprockets", "~> 4.0" # Sprockets is a Rack-based asset packaging system
diff --git a/Gemfile.lock b/Gemfile.lock
index b8360fc88..ff1a9b41e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -733,8 +733,6 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    simpleidn (0.1.1)
-      unf (~> 0.1.4)
     sitemap_generator (6.1.2)
       builder (~> 3.0)
     slack-notifier (2.3.2)
@@ -964,7 +962,6 @@ DEPENDENCIES
   sidekiq-cron (~> 1.1)
   sidekiq-unique-jobs (~> 6.0.25)
   simplecov (= 0.17.1)
-  simpleidn (~> 0.1)
   sitemap_generator (~> 6.1)
   slack-notifier (~> 2.3)
   spring (~> 2.1)
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 6bfc13eea..7dcc73611 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -83,7 +83,8 @@ module ApplicationHelper
 
     return unless (image_url = url.presence || fallback_image)
 
-    Images::Optimizer.call(SimpleIDN.to_ascii(image_url), width: width, quality: quality, fetch_format: fetch_format)
+    normalized_url = Addressable::URI.parse(image_url).normalize.to_s
+    Images::Optimizer.call(normalized_url, width: width, quality: quality, fetch_format: fetch_format)
   end
 
   def optimized_image_tag(image_url, optimizer_options: {}, image_options: {})
diff --git a/spec/helpers/application_helper_spec.rb b/spec/helpers/application_helper_spec.rb
index d447d92f7..336b7d54b 100644
--- a/spec/helpers/application_helper_spec.rb
+++ b/spec/helpers/application_helper_spec.rb
@@ -214,7 +214,7 @@ RSpec.describe ApplicationHelper, type: :helper do
     end
 
     it "returns an ASCII domain for Unicode input" do
-      expect(helper.optimized_image_url("https://www.火.dev/image.png")).to include("https://www.xn--vnx.dev")
+      expect(helper.optimized_image_url("https://www.火.dev/IMAGE.png")).to include("https://www.xn--vnx.dev/IMAGE.png")
     end
 
     it "keeps an ASCII domain as ASCII" do
diff --git a/vendor/cache/simpleidn-0.1.1.gem b/vendor/cache/simpleidn-0.1.1.gem
deleted file mode 100644
index e071d614c..000000000
Binary files a/vendor/cache/simpleidn-0.1.1.gem and /dev/null differ