diff --git a/src/backend/filters/urlRewrite.ts b/src/backend/filters/urlRewrite.ts
index 77c3963..c4bfee5 100644
--- a/src/backend/filters/urlRewrite.ts
+++ b/src/backend/filters/urlRewrite.ts
@@ -38,6 +38,9 @@ export default class URLRewriteFilter implements ContentFilter {
 }
 
 function isICANN(url: string) {
+  if (url.startsWith("//")) {
+    url = `https:${url}`;
+  }
   try {
     const parsedUrl = new URL(url);
     const domain = parsedUrl.hostname;