diff --git a/frontend_tests/node_tests/hash_util.js b/frontend_tests/node_tests/hash_util.js
index 1c27faf7ed..98f50b6d7e 100644
--- a/frontend_tests/node_tests/hash_util.js
+++ b/frontend_tests/node_tests/hash_util.js
@@ -20,12 +20,12 @@ var hamlet = {
 
 people.add_in_realm(hamlet);
 
-var sub = {
+var frontend = {
     stream_id: 99,
     name: 'frontend',
 };
 
-stream_data.add_sub(sub.name, sub);
+stream_data.add_sub('frontend', frontend);
 
 run_test('hash_util', () => {
     // Test encodeHashComponent
@@ -131,7 +131,7 @@ run_test('test_stream_edit_uri', () => {
 run_test('test_by_conversation_and_time_uri', () => {
     var message = {
         type: 'stream',
-        stream: 'frontend',
+        stream_id: frontend.stream_id,
         subject: 'testing',
         id: 42,
     };
diff --git a/static/js/hash_util.js b/static/js/hash_util.js
index 06204c6410..79c58ce0ab 100644
--- a/static/js/hash_util.js
+++ b/static/js/hash_util.js
@@ -43,6 +43,14 @@ exports.encode_operand = function (operator, operand) {
     return exports.encodeHashComponent(operand);
 };
 
+exports.encode_stream_id = function (stream_id) {
+    // stream_data appends the stream name, but it does not do the
+    // URI encoding piece
+    var slug = stream_data.id_to_slug(stream_id);
+
+    return exports.encodeHashComponent(slug);
+};
+
 exports.encode_stream_name = function (operand) {
     // stream_data prefixes the stream id, but it does not do the
     // URI encoding piece
@@ -76,8 +84,8 @@ exports.by_stream_uri = function (stream) {
     return "#narrow/stream/" + exports.encode_stream_name(stream);
 };
 
-exports.by_stream_topic_uri = function (stream, subject) {
-    return "#narrow/stream/" + exports.encode_stream_name(stream) +
+exports.by_stream_topic_uri = function (stream_id, subject) {
+    return "#narrow/stream/" + exports.encode_stream_id(stream_id) +
            "/subject/" + exports.encodeHashComponent(subject);
 };
 
@@ -132,7 +140,7 @@ exports.by_conversation_and_time_uri = function (message) {
 
     if (message.type === "stream") {
         return absolute_url +
-            exports.by_stream_topic_uri(message.stream, message.subject) +
+            exports.by_stream_topic_uri(message.stream_id, message.subject) +
             suffix;
     }
 
diff --git a/static/js/message_list_view.js b/static/js/message_list_view.js
index 3a27a2f75e..056bf820fd 100644
--- a/static/js/message_list_view.js
+++ b/static/js/message_list_view.js
@@ -243,7 +243,7 @@ MessageListView.prototype = {
                         hash_util.by_stream_uri(message_container.msg.stream);
                     message_container.topic_url =
                         hash_util.by_stream_topic_uri(
-                            message_container.msg.stream,
+                            message_container.msg.stream_id,
                             message_container.msg.subject);
                 } else {
                     message_container.pm_with_url =
diff --git a/static/js/stream_data.js b/static/js/stream_data.js
index 3fefdb2f63..097340b2a5 100644
--- a/static/js/stream_data.js
+++ b/static/js/stream_data.js
@@ -97,6 +97,16 @@ exports.get_sub_by_name = function (name) {
     return subs_by_stream_id.get(stream_id);
 };
 
+exports.id_to_slug = function (stream_id) {
+    var name = exports.maybe_get_stream_name(stream_id) || 'unknown';
+
+    // The name part of the URL doesn't really matter, so we try to
+    // make it pretty.
+    name = name.replace(' ', '-');
+
+    return stream_id + '-' + name;
+};
+
 exports.name_to_slug = function (name) {
     var stream_id = exports.get_stream_id(name);
 
diff --git a/static/js/topic_list.js b/static/js/topic_list.js
index 97b4bffc56..a2fadc38d5 100644
--- a/static/js/topic_list.js
+++ b/static/js/topic_list.js
@@ -87,7 +87,7 @@ exports.widget = function (parent_elem, my_stream_id) {
                 unread: num_unread,
                 is_zero: num_unread === 0,
                 is_muted: muting.is_topic_muted(my_stream_id, topic_name),
-                url: hash_util.by_stream_topic_uri(my_stream_name, topic_name),
+                url: hash_util.by_stream_topic_uri(my_stream_id, topic_name),
             };
             var li = $(templates.render('topic_list_item', topic_info));
             self.topic_items.set(topic_name, li);