diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 72681b560e..1c779cd67c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -9,7 +9,8 @@
 * Please see the [README](README.md#schema) for more documentation on the
   YAML Schema.
 * Prior to submitting a pull request, run the tests:
-
+* Advisory filename and the root of the `url:` field must
+  be equal `(as of 5/10/2026).`
 ```
 bundle install
 bundle exec rspec
diff --git a/spec/advisory_example.rb b/spec/advisory_example.rb
index 6097bbfd4a..3c43ddf838 100644
--- a/spec/advisory_example.rb
+++ b/spec/advisory_example.rb
@@ -106,6 +106,24 @@
       it { expect(subject).to be_kind_of(String) }
       it { expect(subject).to_not match(%r{\Ahttp(s)?://osvdb\.org}) }
       it { expect(subject).not_to be_empty }
+
+      it "has a filename that matches the root of the url field" do
+        url = advisory["url"]
+
+        # Extract last path segment from URL
+        url_root = File.basename(URI.parse(url).path)
+
+        # Extract filename without extension
+        filename_root = File.basename(path, ".yml")
+
+        # 5/24/2026: May 9, 2026 is earliest start date with no failed checks.
+        start_date = Date.new(2026, 5, 9)
+        # Skip advisories older than start_date and old OSVDB advisories.
+        if advisory["date"] >= start_date and !filename_root.start_with?("OSVDB")
+          expect(filename_root).to eq(url_root),
+            "Expected filename '#{filename_root}' DOES NOT to match URL root '#{url_root}'"
+        end
+      end
     end
 
     describe "title" do