diff --git a/zephyr/static/js/hashchange.js b/zephyr/static/js/hashchange.js
index d2efc39b35..982e96d3d9 100644
--- a/zephyr/static/js/hashchange.js
+++ b/zephyr/static/js/hashchange.js
@@ -9,11 +9,11 @@ var changing_hash = false;
 // window.location.hash.  So we hide our URI-encoding
 // by replacing % with . (like MediaWiki).
 
-function encodeHashComponent(str) {
+exports.encodeHashComponent = function(str) {
     return encodeURIComponent(str)
         .replace(/\./g, '%2E')
         .replace(/%/g,  '.');
-}
+};
 
 function decodeHashComponent(str) {
     return decodeURIComponent(str.replace(/\./g, '%'));
@@ -45,8 +45,8 @@ exports.save_narrow = function (operators) {
     } else {
         var new_hash = '#narrow';
         $.each(operators, function (idx, elem) {
-            new_hash += '/' + encodeHashComponent(elem[0])
-                      + '/' + encodeHashComponent(elem[1]);
+            new_hash += '/' + hashchange.encodeHashComponent(elem[0])
+                      + '/' + hashchange.encodeHashComponent(elem[1]);
         });
         exports.changehash(new_hash);
     }
diff --git a/zephyr/static/js/subs.js b/zephyr/static/js/subs.js
index 0da405e669..207a180707 100644
--- a/zephyr/static/js/subs.js
+++ b/zephyr/static/js/subs.js
@@ -237,7 +237,7 @@ function create_sub(stream_name, attrs) {
 
     add_sub(stream_name, sub);
     if (sub.subscribed) {
-        ui.add_narrow_filter(stream_name, "stream", "#narrow/stream/" + encodeURIComponent(stream_name));
+        ui.add_narrow_filter(stream_name, "stream", "#narrow/stream/" + hashchange.encodeHashComponent(stream_name));
     }
     return sub;
 }
@@ -285,7 +285,7 @@ function mark_subscribed(stream_name, attrs) {
         set_color(stream_name, pick_color());
         mark_color_used(sub.color);
         // This will do nothing on MIT
-        ui.add_narrow_filter(stream_name, "stream", "#narrow/stream/" + encodeURIComponent(stream_name));
+        ui.add_narrow_filter(stream_name, "stream", "#narrow/stream/" + hashchange.encodeHashComponent(stream_name));
         var settings = settings_for_sub(sub);
         var button = button_for_sub(sub);
         if (button.length !== 0) {