diff --git a/lib/forum-activity.js b/lib/forum-activity.js
index db608603e..ada71c949 100644
--- a/lib/forum-activity.js
+++ b/lib/forum-activity.js
@@ -20,12 +20,17 @@ async function recursiveFetchDiscourse(url, before = null, acc = []) {
 }
 
 async function fetchForum(url) {
-  if (!url.match(/discourse/) && !url.match(/socialhub\.activitypub\.rocks/)) return "Did not fetch forum at " + url;
-  // TODO: fix case where discourse URL is for a specific category à la
-  // https://discourse.wicg.io/c/web-mapping
-  // TODO: detect if forum is discourse more reliably?
+  if (url.match(/slack\.com\//) || url.match(/google.com\//)) {
+    return `Forum ${url} is hosted on a non-supported platform`;
+  }
   if (url.endsWith("/")) url = url.slice(0, -1);
-  return {items: await recursiveFetchDiscourse(url + '/posts.json')};
+  try {
+    return {items: await recursiveFetchDiscourse(url + '/posts.json')};
+  } catch (e) {
+    return `Did not recognize discourse API for ${url}`;
+  }
+  // TODO: handle case where discourse URL is for a specific category à la
+  // https://discourse.wicg.io/c/web-mapping
 }
 
 module.exports.fetchForum = fetchForum;
diff --git a/test/forum-activity.js b/test/forum-activity.js
index d576efbb3..c715c19a8 100644
--- a/test/forum-activity.js
+++ b/test/forum-activity.js
@@ -16,7 +16,7 @@ const agent = new MockAgent();
 let counter = 0;
 const testUrl = () => {
   counter++;
-  return new URL(`https://example.test/discourse/mail${counter}/`);
+  return new URL(`https://example.test/disc/mail${counter}/`);
 }
 
 const toDiscourseAPI = p => p + 'posts.json';
@@ -45,6 +45,14 @@ describe('The Forum Activity monitor', function () {
     assert.equal(data[0].created_at, "2023-11-01T21:30:42.605Z", 'Date retrieved from discourse post');
   });
 
+  it('skips Google Groups and Slacks', async function() {
+    const data = await fetchForum("https://groups.google.com/g/test");
+    assert.equal(typeof data, 'string');
+    const data2 = await fetchForum("https://test.slack.com/channel");
+    assert.equal(typeof data2, 'string');
+  });
+
+  
   /*
   it("returns an error when the archive doesn't exist", async function() {
     const u = testUrl();