diff --git a/lib/upload_creator.rb b/lib/upload_creator.rb
index d2708108530..55f690c635e 100644
--- a/lib/upload_creator.rb
+++ b/lib/upload_creator.rb
@@ -72,8 +72,10 @@ class UploadCreator
         extract_image_info!
         return @upload if @upload.errors.present?
 
-        if @image_info.type.to_s == "svg"
+        if @image_info.type == :svg
           clean_svg!
+        elsif @image_info.type == :ico
+          convert_favicon_to_png!
         elsif !Rails.env.test? || @opts[:force_optimize]
           convert_to_jpeg! if convert_png_to_jpeg? || should_alter_quality?
           fix_orientation! if should_fix_orientation?
@@ -261,6 +263,33 @@ class UploadCreator
   MIN_CONVERT_TO_JPEG_BYTES_SAVED = 75_000
   MIN_CONVERT_TO_JPEG_SAVING_RATIO = 0.70
 
+  def convert_favicon_to_png!
+    png_tempfile = Tempfile.new(["image", ".png"])
+
+    from = @file.path
+    to = png_tempfile.path
+
+    OptimizedImage.ensure_safe_paths!(from, to)
+
+    from = OptimizedImage.prepend_decoder!(from, nil, filename: "image.#{@image_info.type}")
+    to = OptimizedImage.prepend_decoder!(to)
+
+    from = "#{from}[-1]" # We only want the last(largest) image of the .ico file
+
+    opts = { flatten: false } # Preserve transparency
+
+    begin
+      execute_convert(from, to, opts)
+    rescue
+      # retry with debugging enabled
+      execute_convert(from, to, opts.merge(debug: true))
+    end
+
+    @file.respond_to?(:close!) ? @file.close! : @file.close
+    @file = png_tempfile
+    extract_image_info!
+  end
+
   def convert_to_jpeg!
     return if @opts[:for_site_setting]
     return if filesize < MIN_CONVERT_TO_JPEG_BYTES_SAVED
@@ -331,8 +360,8 @@ class UploadCreator
       "-auto-orient",
       "-background", "white",
       "-interlace", "none",
-      "-flatten"
     ]
+    command << "-flatten" unless opts[:flatten] == false
     command << "-debug" << "all" if opts[:debug]
     command << "-quality" << opts[:quality].to_s if opts[:quality]
     command << to
diff --git a/spec/lib/upload_creator_spec.rb b/spec/lib/upload_creator_spec.rb
index 2be20fe13ae..bf7899d75ef 100644
--- a/spec/lib/upload_creator_spec.rb
+++ b/spec/lib/upload_creator_spec.rb
@@ -547,6 +547,23 @@ RSpec.describe UploadCreator do
     end
   end
 
+  describe '#convert_favicon_to_png!' do
+    let(:filename) { "smallest.ico" }
+    let(:file) { file_from_fixtures(filename, "images") }
+
+    before do
+      SiteSetting.authorized_extensions = 'png|jpg|ico'
+    end
+
+    it 'converts to png' do
+      upload = UploadCreator.new(file, filename).create_for(user.id)
+
+      expect(upload.persisted?).to eq(true)
+      expect(upload.extension).to eq('png')
+    end
+
+  end
+
   describe '#clean_svg!' do
     let(:b64) do
       Base64.encode64('<svg onmouseover="alert(alert)" />')