diff --git a/spec/system/image_signatures_spec.rb b/spec/system/image_signatures_spec.rb
index 0c6500d..55147f2 100644
--- a/spec/system/image_signatures_spec.rb
+++ b/spec/system/image_signatures_spec.rb
@@ -4,7 +4,7 @@ RSpec.describe "Image signatures", type: :system do
   fab!(:user)
   fab!(:topic) { Fabricate(:topic, category: Fabricate(:category)) }
   fab!(:post) { Fabricate(:post, topic:) }
-  let(:signature_image_url) { "https://example.com/signature.png" }
+  let(:signature_image_url) { "data:abcdef," }
 
   context "when signatures plugin is enabled" do
     before do