diff --git a/app/controllers/uploads_controller.rb b/app/controllers/uploads_controller.rb
index d1251784ffd..ad5b551a051 100644
--- a/app/controllers/uploads_controller.rb
+++ b/app/controllers/uploads_controller.rb
@@ -67,10 +67,14 @@ class UploadsController < ApplicationController
 
       # allow users to upload large images that will be automatically reduced to allowed size
       if SiteSetting.max_image_size_kb > 0 && FileHelper.is_image?(filename) && File.size(tempfile.path) > 0
+        attempt = 2
         allow_animation = type == "avatar" ? SiteSetting.allow_animated_avatars : SiteSetting.allow_animated_thumbnails
-        attempt = 5
         while attempt > 0 && File.size(tempfile.path) > SiteSetting.max_image_size_kb.kilobytes
-          OptimizedImage.downsize(tempfile.path, tempfile.path, "80%", filename: filename, allow_animation: allow_animation)
+          image_info = FastImage.new(tempfile.path) rescue nil
+          w, h = *(image_info.try(:size) || [0, 0])
+          break if w == 0 || h == 0
+          dimensions = "#{(w * 0.8).floor}x#{(h * 0.8).floor}"
+          OptimizedImage.downsize(tempfile.path, tempfile.path, dimensions, filename: filename, allow_animation: allow_animation)
           attempt -= 1
         end
       end