diff --git a/src/utils/__tests__/matchAndRewriteRoute.test.ts b/src/utils/__tests__/matchAndRewriteRoute.test.ts
index 815f83b3..d92811cf 100644
--- a/src/utils/__tests__/matchAndRewriteRoute.test.ts
+++ b/src/utils/__tests__/matchAndRewriteRoute.test.ts
@@ -232,6 +232,22 @@ describe('matchAndRewriteURL', () => {
       expect(url4.toString()).toEqual('https://localhost/googleapis/foo/v1/test:url?key=abc123');
     });
 
+    it('Matches port parameters and remaps them properly', () => {
+      const url = attemptRemap({
+        url: new URL('https://foo.domain.com:4567/'),
+        mappings: [{prefix: '/domain/{subdomain}/{port}', target: '{subdomain}.domain.com:{port}'}],
+      });
+      expect(url.toString()).toEqual('https://localhost/domain/foo/4567/');
+    });
+
+    it('Does not remove port when url is not matched', () => {
+      const url = attemptRemap({
+        url: new URL('https://foo.domain.com:4567/'),
+        mappings: [],
+      });
+      expect(url.toString()).toEqual('https://foo.domain.com:4567/');
+    });
+
     it('Applies the /.proxy/ mapping without any mappings', () => {
       const url = attemptRemap({
         url: new URL('https://1234567890.discordsays.com/api/token'),
diff --git a/src/utils/url.ts b/src/utils/url.ts
index f67f4ed2..809e0a67 100644
--- a/src/utils/url.ts
+++ b/src/utils/url.ts
@@ -15,6 +15,10 @@ function regexFromTarget(target: string): RegExp {
   return new RegExp(`${regexString}(/|$)`);
 }
 
+function removePortParameterFromTarget(url: string): string {
+  return url.replace(/:\{[^}]+\}/g, '');
+}
+
 export interface MatchAndRewriteURLInputs {
   originalURL: URL;
   prefixHost: string;
@@ -32,15 +36,17 @@ export interface MatchAndRewriteURLInputs {
  * @returns  null if URL doesn't match prefix, otherwise return rewritten URL
  */
 export function matchAndRewriteURL({originalURL, prefix, prefixHost, target}: MatchAndRewriteURLInputs): URL | null {
-  // coerce url with filler https protocol so we can retrieve host and pathname from target
-  const targetURL = new URL(`https://${target}`);
+  // Remove port parameter from target and coerce url with filler https protocol so we can retrieve host and pathname from target
+  const targetURL = new URL(`https://${removePortParameterFromTarget(target)}`);
   // Depending on the environment, the URL constructor may turn `{` and `}` into `%7B` and `%7D`, respectively
-  const targetRegEx = regexFromTarget(targetURL.host.replace(/%7B/g, '{').replace(/%7D/g, '}'));
+  const targetRegEx = regexFromTarget(target.replace(/%7B/g, '{').replace(/%7D/g, '}'));
   const match = originalURL.toString().match(targetRegEx);
   // Null match indicates that this target is not relevant
   if (match == null) return originalURL;
   const newURL = new URL(originalURL.toString());
   newURL.host = prefixHost;
+  // Remove port from new url (discord activities proxy doesn't listen on custom ports)
+  newURL.port = '';
   newURL.pathname = prefix.replace(SUBSTITUTION_REGEX, (_, matchName) => {
     const replaceValue = match.groups?.[matchName];
     if (replaceValue == null) throw new Error('Misconfigured route.');