diff --git a/app/models/html_variant.rb b/app/models/html_variant.rb
index 0ee6a86ee..0d383fd1d 100644
--- a/app/models/html_variant.rb
+++ b/app/models/html_variant.rb
@@ -75,6 +75,6 @@ class HtmlVariant < ApplicationRecord
   end
 
   def allowed_image_host?(src)
-    src.start_with?("https://res.cloudinary.com/")
+    src.start_with?("https://res.cloudinary.com/") || src.start_with?(Images::Optimizer.get_imgproxy_endpoint)
   end
 end
diff --git a/app/services/images/optimizer.rb b/app/services/images/optimizer.rb
index 9ef1ae1aa..c06ace3d8 100644
--- a/app/services/images/optimizer.rb
+++ b/app/services/images/optimizer.rb
@@ -66,7 +66,7 @@ module Images
         # On other environments, rely on ApplicationConfig for a
         # more flexible configuration
         # ie. default imgproxy endpoint is localhost:8080
-        ApplicationConfig["IMGPROXY_ENDPOINT"]
+        ApplicationConfig["IMGPROXY_ENDPOINT"] || "http://localhost:8080"
       end
     end
   end
diff --git a/spec/models/html_variant_spec.rb b/spec/models/html_variant_spec.rb
index 0a4f605be..00be54dad 100644
--- a/spec/models/html_variant_spec.rb
+++ b/spec/models/html_variant_spec.rb
@@ -55,4 +55,19 @@ RSpec.describe HtmlVariant, type: :model do
     cloudinary_string = "/c_limit%2Cf_auto%2Cfl_progressive%2Cq_auto%2Cw_420/https://devimages.com/image.jpg"
     expect(html_variant.html).to include(cloudinary_string)
   end
+
+  it "does not add prefix if it already starts with cloudinary" do
+    allow(Images::Optimizer).to receive(:call)
+    html = %(<img src="https://res.cloudinary.com/image.jpg">)
+    html_variant.update(approved: false, html: html)
+    expect(Images::Optimizer).not_to have_received(:call)
+  end
+
+  it "does not add prefix if already on site root" do
+    allow(Images::Optimizer).to receive(:call)
+    html = "<img src=\"#{Images::Optimizer.get_imgproxy_endpoint}/image.jpg\">"
+    html_variant.update(approved: false, html: html)
+    html_variant.save
+    expect(Images::Optimizer).not_to have_received(:call)
+  end
 end