diff --git a/frontend_tests/node_tests/stream_data.js b/frontend_tests/node_tests/stream_data.js
index 7f470541dc..c1de522183 100644
--- a/frontend_tests/node_tests/stream_data.js
+++ b/frontend_tests/node_tests/stream_data.js
@@ -116,7 +116,12 @@ run_test("basics", () => {
     assert.equal(stream_data.slug_to_name("2-whatever"), "social");
     assert.equal(stream_data.slug_to_name("2"), "social");
 
+    // legacy
     assert.equal(stream_data.slug_to_name("25-or-6-to-4"), "25-or-6-to-4");
+    assert.equal(stream_data.slug_to_name("2something"), "2something");
+
+    assert.equal(stream_data.slug_to_name("99-whatever"), "99-whatever");
+    assert.equal(stream_data.slug_to_name("99whatever"), "99whatever");
 });
 
 run_test("renames", () => {
diff --git a/static/js/stream_data.js b/static/js/stream_data.js
index 161367f221..98ef48b97e 100644
--- a/static/js/stream_data.js
+++ b/static/js/stream_data.js
@@ -328,7 +328,7 @@ exports.slug_to_name = function (slug) {
     GitHub conversations.  We migrated to modern slugs in
     early 2018.
     */
-    const m = /^(\d+)(-.*)?/.exec(slug);
+    const m = /^(\d+)(-.*)?$/.exec(slug);
     if (m) {
         const stream_id = Number.parseInt(m[1], 10);
         const sub = subs_by_stream_id.get(stream_id);